System for displaying information related to a flight of an aircraft and associated method

ABSTRACT

A system for displaying information related to a flight of an aircraft and an associated method are provided. The display system comprises a display device, a man-machine interface, a module for dynamically generating synthesis images, each comprising a synthetic depiction of the environment and a curve representative of a trajectory, said module being configured to generate a first synthesis image centered around a first central point of interest, to command the display thereof, and to detect an action to modify the central point of interest by an operator via said man-machine interface. The generating module is also configured to determine, as a function of said modification action, a second central point of interest, situated along said curve whatever said modification action is, to generate a second synthesis image centered around said second central point of interest, and to command the display thereof.

This claims the benefit of French Patent Application FR 15 01021, filedMay 19, 2015 and hereby incorporated by reference herein.

The present invention relates to a system for displaying informationrelated to a flight of an aircraft, said system comprising:

-   -   a display device,    -   a module for dynamically generating synthesis images, configured        to generate synthesis images, each synthesis image comprising a        synthetic depiction of the environment situated in the vicinity        of a trajectory of the aircraft and a curve representative of a        trajectory of the aircraft, said curve being superimposed on        said synthetic depiction, said generating module being        configured to generate a first synthesis image centered around a        first central point of interest and to command the display, on        said display device, of said first synthesis image,    -   a man-machine interface,        said generating module being configured to detect a modification        action to modify the central point of interest by an operator        via said man-machine interface.

Such a system is for example designed to be installed in the cockpit ofan aircraft to be associated with a viewer of the cockpit, or on theground, in particular in a ground station, for example in a missionpreparation system. The viewer device is for example a head down monitorintegrated into the dashboard of the cockpit, or a monitor of a missionpreparation system.

BACKGROUND

To facilitate the piloting of the aircraft, and to give the pilot globalinformation about the structure of the terrain situated opposite theaircraft, it is known to generate synthetic images of the landscapearound the aircraft, in particular from topographical databases, basedon the current position of the aircraft determined by the navigationsystem of the aircraft.

The synthetic images generally comprise a synthetic surface depiction ofthe terrain. Such a display system allows the operator to see the reliefthat may be found around the aircraft, and may also make it possible forthe operator to move the point on which the image is centered in orderto view terrain zones located around the position of the aircraft, or toresolve an ambiguity.

The synthetic images are for example three-dimensional images, showingthe trajectory of the aircraft and the surrounding terrain according toa first type of perspective making it possible to provide the operatoror a pilot with a clear depiction of the situation of the aircraftrelative to its environment. Such images make it possible to improve theoperator's awareness of the situation and simplify his decision-makingprocess, in particular by preventing the operator from having tomentally reconstruct the necessary three-dimensional information fromimages seen from above and the side.

The synthetic images can also be seen according to a second type ofperspective, for example vertical and/or horizontal views of thetrajectory of the aircraft, i.e., top or side views of that trajectory.Such images are for example two-dimensional. Such images are moreparticularly suitable for precision activities, in particular forviewing the vertical trajectory of the aircraft during an ascent ordescent phase, or to redefine the passage points of the flight plan.

SUMMARY OF THE INVENTION

Such a display system provides substantial assistance to the operator,but its manipulation may cause an unwanted additional workload for theoperator. In particular, when an operator moves the point on which theimage is centered, this movement is not constrained, and the operatormay be led to display zones of the terrain far from the position of theaircraft and its trajectory, and that are of little interest.

One aim of the invention is therefore to provide a system for viewinginformation related to a flight by an aircraft that is capable ofdisplaying, at any moment, an image showing the relevant information foran operator, while minimizing the workload necessary to display such animage.

To that end, the invention relates to a system of the aforementionedtype, characterized in that said generating module is further configuredto:

-   -   determine, as a function of said modification action, a second        central point of interest, situated along said curve, said        second central point of interest being situated along said curve        whatever said modification action is,    -   generate a second synthesis image centered around said second        central point of interest, and    -   command the display, on said display device, of said second        synthesis image.

The system according to the invention may comprise one or more of thefollowing features, considered alone or according to any technicallypossible combination:

-   -   said modification action to modify the central point of interest        comprises a movement of a member by the operator between a first        position and a second position;    -   said first central point of interest is situated along said        curve, and said modification action to modify the central point        of interest comprises a movement of a member by the operator        between a first position and a second position in a direction        not parallel to the tangent to said curve at said first central        point of interest;    -   said first central point of interest is situated along said        curve, and said generating module is configured to:        -   determine, as a function of a movement vector between said            first position and said second position, a curvilinear            distance on said curve between said first central point of            interest and said second central point of interest, and to        -   determine, from a position on the curve of said first            central point of interest and said curvilinear distance, a            position on the curve of said second central point of            interest.    -   said generating module is configured to determine said        curvilinear distance as a function of said movement vector and a        vector tangent to said curve at said initial central point of        interest, in particular as a function of a scalar product        between a projection of said movement vector over a horizontal        plane of said first synthesis image and said tangent vector;    -   said synthesis images are three-dimensional images, said        synthetic depiction of the environment being a three-dimensional        depiction and said curve being a three-dimensional curve;    -   said first synthesis image is seen from a first point of view,        and said module is configured to detect a rotation action of the        position of said point of view relative to said first central        point of interest in a vertical plane, in a horizontal plane,        respectively, said rotation action comprising a movement of a        member by an operator in a vertical direction, in a horizontal        direction, respectively;    -   said generating module further being configured to determine, as        a function of said rotation action, a modified point of view, to        generate a modified synthesis image seen from said modified        point of view, and to command the display, on said display        device, of said modified synthesis image;    -   said generating module is configured to display a vertical slide        and/or a horizontal slide on said first synthesis image, and        said rotation action comprises a movement of a member by an        operator on said vertical slide, said horizontal slide,        respectively, in a vertical direction, in a horizontal        direction, respectively;    -   said man-machine interface comprises a tactile control device;    -   said action to modify the central point of interest comprises a        movement of said member by the operator between the first        position and the second position on said tactile control device;    -   said display device comprises a touchscreen, and comprises said        tactile control device.

The invention also relates to a method for displaying informationrelated to a flight of an aircraft, said method being characterized inthat it comprises the following successive steps:

-   -   displaying, on a display device, a first synthesis image        comprising a synthetic depiction of the environment situated in        the vicinity of a trajectory of the aircraft and a curve        representative of a trajectory of the aircraft, said curve being        superimposed on said synthetic depiction, said first synthesis        image being centered around a first central point of interest,    -   detecting a modification action to modify the central point of        interest by an operator via a man-machine interface,    -   determining, as a function of said modification action, a second        central point of interest, situated along said curve,    -   generating a second synthesis image centered around said second        central point of interest,    -   displaying said second synthesis image on said display device.

The method according to the invention may comprise one or more of thefollowing features, considered alone or according to any technicallypossible combination:

-   -   said modification action to modify the central point of interest        comprises a movement of a member by an operator between a first        position and a second position;    -   said first central point of interest is situated along said        curve, and said modification action to modify the central point        of interest comprises a movement of a member by an operator        between a first position and a second position in a direction        not parallel to the tangent to said curve at said first central        point of interest;    -   said modification action to modify the central point of interest        comprises a movement of said member by the operator between the        first position and the second position on a touchscreen;    -   said first central point of interest is situated along said        curve, and the step for determining said second central point of        interest comprises:        -   a phase for determining, as a function of a movement vector            between said first position and said second position, a            curvilinear distance on said curve between said first            central point of interest and said second central point of            interest, and        -   a phase for determining, from a position on the curve of            said first central point of interest and said curvilinear            distance, said second central point of interest.    -   said curvilinear distance is determined as a function of said        movement vector and a vector tangent to said curve at said        initial central point of interest, in particular as a function        of a scalar product between a projection of said movement vector        over a horizontal plane of said first synthesis image and said        tangent vector.

According to a second aspect, the invention relates to a system fordisplaying information related to a flight of an aircraft, said systemcomprising:

-   -   a tactile control device;    -   a generating module, configured to dynamically generate        synthesis images, each synthesis image comprising a depiction of        the environment situated in the vicinity of a trajectory of the        aircraft, said generating module being able to generate a first        synthesis image comprising a depiction of the environment        according to a first scale, and to command the display, on a        display device, of said first synthesis image,        said generating module being configured to:    -   detect a scale modification action by an operator via said        tactile control device, said scale modification action        comprising a movement of two control members on said tactile        control device opposite two points of a surface of said tactile        control device,    -   when a scale modification action is detected, determine a scale        modification factor of the synthesis image,

said system being characterized in that said generating module isconfigured to determine the scale modification factor at each moment,during said modification action:

-   -   as a function of a distance between said two points if said two        points are comprised in a first predefined zone of said surface        at said moment, and    -   if at least one of said two points is not comprised in said        first zone at said moment, as a function of a maintenance        duration of said point outside said first zone.

The system according to this second aspect may comprise one or more ofthe following features, considered alone or according to any technicallypossible combination:

-   -   said generating module is further configured to determine a        second scale by applying said modification factor to said first        scale, and to generate a second synthesis image according to        said second scale,    -   said synthesis images are three-dimensional synthesis images        depicted according to a first type of perspective, and the scale        of each synthesis image is defined by an observation distance        between a central point of interest on which said synthesis        image is centered and a point of view from which that synthesis        image is seen,    -   said first scale being defined by a first observation distance        between a first central point of interest on which said first        synthesis image is centered and a first point of view from which        said first synthesis image is seen, said generating module is        configured to determine a second observation distance by        applying said modification factor to said first observation        distance, and to generate a second synthesis image centered on        the second central point of interest and seen from a second        point of view situated at said second observation distance from        said second central point of interest,    -   said synthesis images are synthesis images depicted according to        a second type of perspective, and the scale of each synthesis        image is defined by a ratio between an apparent dimension of        said synthesis image when said synthesis image is displayed on        said display device and a corresponding actual dimension of the        environment shown in said synthesis image,    -   said first scale being defined by a first ratio between an        apparent dimension of said first synthesis image when said first        synthesis image is displayed on said display device and a first        corresponding actual dimension of the environment depicted in        the first synthesis image, said generating module is configured        to determine a second ratio by applying said modification factor        to said first ratio, and to generate a second synthesis image so        that the ratio between the apparent dimension of said second        synthesis image when said second synthesis image is displayed on        said display device and a corresponding actual second dimension        of the environment depicted on said second synthesis image is        equal to said second ratio,    -   said generating module is configured to determine the scale        modification factor independently of the distance between said        two points if at least one of said two points is not comprised        in said first zone,    -   said generating module is configured to detect an initial        positioning of said control members opposite two initial points,        and to detect, at each moment, a position of the points opposite        which said control members are positioned at that moment,    -   said generating module is configured to determine, when said        initial positioning is detected, said first zone, as a function        of the position of said initial points,    -   said first zone includes said initial points,    -   said generating module is configured to determine, when said        initial positioning is detected, a first closed curve and a        second closed curve situated inside said first closed curve,        said first zone being formed by all of the points situated        inside said first closed curve and outside said second closed        curve;    -   said generating module is configured to determine said scale        modification factor as a function of the distance between said        two points as long as said two points are comprised in said        first zone, then, when at least one of said two points leaves        said first zone, to determine the scale modification factor as a        function of the maintenance duration of said point outside said        first zone;    -   if said control members are positioned on said tactile control        device opposite points comprised in said first zone, said        generating module is configured to determine the scale        modification factor as a function of the ratio between the        distance between said initial points and the distance between        these points,    -   if said control members are positioned on said tactile control        device opposite points comprised in said first zone, said scale        modification factor is a strictly monotonous function of the        deviation between the distance between said points and the        distance between said initial points,    -   if at least one of said control members is positioned on said        tactile control device opposite a point not comprised in said        first zone, said generating module is configured to determine        the scale modification factor as a strictly monotonous function        of the maintenance duration of said member opposite a point not        comprised in said first zone,    -   if at least one of said control members is positioned on said        tactile control device opposite a point not comprised in said        first zone, said generating module is configured to determine        the scale modification factor as a strictly increasing and        convex function of the maintenance duration of said member        opposite a point not comprised in said first zone,    -   if at least one of said control members is positioned on said        touchscreen opposite a point not comprised in said first zone,        said generating module is configured to determine the scale        modification factor as a strictly decreasing and concave        function of the maintenance duration of said member opposite a        point not comprised in said first zone.

The invention also relates to a method for displaying informationrelated to a flight of an aircraft, said method comprising:

-   -   a step for generating a first synthesis image comprising a        depiction of the environment situated in a vicinity of a        trajectory of the aircraft according to a first scale,    -   a step for displaying said first synthesis image on a display        device,    -   a step for detecting a scale modification action by an operator        a said tactile control device, said modification action        comprising a movement of two control members on said tactile        control device opposite two points of a surface of said tactile        control device,    -   a step for determining a scale modification factor of the        synthesis image, said modification factor being determined as a        function of a distance between said points if said points are        comprised in a first predefined zone of said control device, or,        if at least one of said points is not comprised in said first        zone, as a function of the maintenance duration of said point        outside said first zone.

This method may comprise one or more of the following features,considered alone or according to any technically possible combination:

-   -   the method further comprises a step for determining a second        scale by applying said modification factor to said first scale,        and for generating a second synthesis image on said second        scale,    -   said synthesis images are three-dimensional synthesis images        depicted according to a first type of perspective, and the scale        of each synthesis image is defined by an observation distance        between a central point of interest on which said synthesis        image is centered and a point of view from which that synthesis        image is seen,    -   said first scale being defined by a first observation distance        between a first central point of interest on which said first        synthesis image is centered and a first point of view from which        said first synthesis image is seen, said determining step        comprises determining a second observation distance by applying        said modification factor to said first observation distance, and        said second synthesis image is centered on the second central        point of interest and seen from a second point of view situated        at said second observation distance from said second central        point of interest,    -   said synthesis images are synthesis images depicted according to        a second type of perspective, and the scale of each synthesis        image is defined by a ratio between an apparent dimension of        said synthesis image and a corresponding actual dimension of the        environment shown in said synthesis image,    -   said first scale being defined by a first ratio between an        apparent dimension of said first synthesis image when said first        synthesis image is displayed on said display device and a first        corresponding actual dimension of the environment depicted in        the first synthesis image, said determining step comprises        determining a second ratio by applying said modification factor        to said first ratio, and said second synthesis image is such        that the ratio between the apparent dimension of said second        synthesis image and a corresponding actual second dimension of        the environment depicted in said second synthesis image is equal        to said second ratio,    -   said method comprises a first step for determining a scale        modification factor of the synthesis image as a function of the        distance between said points, said points being comprised in        said first predefined zone of said synthesis image, then, at        least one of said points being situated outside said first zone,        a second step for determining a scale modification factor of the        synthesis image as a function of the maintenance duration of        said point outside the first zone.

According to a third aspect, the invention relates to a system fordisplaying information related to a flight of an aircraft, said systemcomprising a generating module for dynamically generating synthesisimages, configured to generate three-dimensional synthesis images, eachthree-dimensional synthesis image comprising a synthetic depiction ofthe environment situated in the vicinity of a trajectory of theaircraft, and a curve representative of a trajectory portion of theaircraft, said curve being superimposed on said synthetic depiction,each three-dimensional synthetic image being from a given point of view,said system being characterized in that said generating module isconfigured to determine an optimal position of said point of view suchthat a length of to portion of the trajectory of the aircraft visible ina three-dimensional synthesis image seen from a point of view at saidoptimal position is maximized.

This system may comprise one or more of the following features,considered alone or according to any technically possible combination:

-   -   said generating module is configured to generate an optimized        three-dimensional synthesis image seen from an optimal point of        view situated at said optimal position and to command the        display thereof by a display device;    -   each three-dimensional synthesis image being centered on a        central point of interest, the position of a point of view is        defined by:        -   an observation distance between said point of view and said            central point of interest, and        -   at least one angular position corresponding to an angle            formed between a direction between said point of view and            said central point of interest and a predetermined plane;    -   said observation distance being fixed, said generating module is        configured to determine an optimal position of said point of        view such that the length of the portion of the trajectory of        the aircraft visible in a three-dimensional synthesis image seen        from a point of view situated at said observation distance from        the point of view and at said optimal angular position is        maximized;    -   the position of any point of view is defined by said observation        distance between that point of view, a vertical angular position        of said point of view, and a horizontal angular position of said        point of view;    -   said observation distance and said vertical angular position        being fixed, said generating module is configured to determine        an optimal horizontal angular position of said point of view        such that the length of the portion of the trajectory of the        aircraft visible in a three-dimensional synthesis image seen        from a point of view situated at said observation distance from        the point of view, at said vertical angular position and at said        optimal horizontal angular position is maximized;    -   said horizontal angular position corresponds to an angle formed        between the direction between said point of view and said        central point of interest and a predetermined vertical plane;    -   said horizontal vertical angular position corresponds to an        angle formed between the direction between said point of view        and said central point of interest and a horizontal plane;    -   each three-dimensional synthesis image is seen according to a        predefined fixed opening angle;    -   said optimal position is such that a predefined set of points of        interest is visible in the three-dimensional synthesis image        seen from a point of view at said optimal position.    -   in order to determine said optimal position, said generating        module is configured to:        -   determine a set of successive points of the trajectory,        -   from an initial position of said point of view, iteratively            determine a plurality of successive modified positions of            the point of view, each modified position being determined            such that an additional point of said plurality of            successive points is visible in a synthesis image seen from            a modified point of view in said modified position, the            points of said plurality of successive points situated            downstream from the trajectory relative to said additional            point remaining visible in said synthesis image;    -   said generating module is configured to determine said plurality        of successive modified positions of the point of view until no        modified position of the point of view makes it possible to        show, in a synthesis image, an additional point of said        plurality of successive points without at least one point of        said plurality of successive points situated downstream from the        trajectory relative to said additional point no longer being        visible.

The invention also relates to a method for displaying informationrelated to a flight by an aircraft, said method comprising generating athree-dimensional synthesis image comprising a synthetic depiction ofthe environment situated in the vicinity of a trajectory of theaircraft, and a curve representative of a trajectory portion of theaircraft, said curve being superimposed on said synthetic depiction,said three-dimensional synthetic image being seen from a point of view,said method being characterized in that it comprises a step fordetermining an optimal position of said point of view, said optimalposition being such that a length of a portion of the trajectory of theaircraft visible in a three-dimensional synthesis image seen from apoint of view at said optimal position is maximized.

This method may comprise one or more of the following features,considered alone or according to any technically possible combination:

-   -   said method further comprises a step for displaying an optimized        three-dimensional synthesis image seen from an optimal point of        view situated at said optimal position by a display device;    -   each three-dimensional synthesis image being centered on a        central point of interest, the position of a point of view is        defined by:        -   an observation distance between said point of view and said            central point of interest, and        -   at least one angular position corresponding to an angle            formed between a direction between said point of view and            said central point of interest and a predetermined plane;    -   said observation distance being fixed, the step for determining        said optimal position comprises the determination of an optimal        angular position of said point of view such that the length of        the portion of the trajectory of the aircraft visible in a        three-dimensional synthesis image seen from a point of view        situated at said observation distance from the point of view and        at said optimal angular position is maximized;    -   the position of any point of view is defined by said observation        distance between that point of view, a vertical angular position        of said point of view, and a horizontal angular position of said        point of view;    -   said observation distance and said vertical angular position        being fixed, the step for determining said optimal position        comprises the determination of an optimal horizontal angular        position of said point of view such that the length of the        portion of the trajectory of the aircraft visible in a        three-dimensional synthesis image seen from a point of view        situated at said observation distance from the point of view, at        said vertical angular position and at said optimal horizontal        angular position is maximized;    -   said step for determining said optimal position comprises:        -   a phase for determining a set of successive points of the            trajectory,        -   from an initial position of said point of view, a phase for            determining a modified position of the point of view, such            that at the end of said phase, a first point of said            plurality of successive points is visible in a synthesis            image seen from a modified point of view situated in said            modified position;    -   said step for determining said optimal position further        comprises a plurality of successive additional phases for        determining a modified point of view, such that at the end of        each of said phases, an additional point of said plurality of        successive points is visible in a synthesis image seen from a        modified point of view situated in said modified position, the        points of said plurality of successive points situated        downstream from the trajectory relative to said additional point        remaining visible in said synthesis image.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood upon reading the followingdescription, provided solely as an example and done in reference to thedrawings, in which:

FIG. 1 diagrammatically illustrates a display system according to oneembodiment of the invention;

FIG. 2 diagrammatically shows a three-dimensional synthesis imageaccording to a first type of perspective;

FIG. 3 is a diagrammatic view of a synthesis image according to a secondtype of perspective, seen from above;

FIG. 4 shows several example depictions of symbolic objects, accordingto the first and second types of perspective;

FIG. 5 illustrates an example depiction of a symbolic objectrepresentative of the position of the aircraft according to the firstand second types of perspective;

FIG. 6 illustrates an example three-dimensional depiction of a symbolicimage representative of a cloud and a storm cell according to the firsttype of perspective;

FIG. 7 is a diagram illustrating the definition of zones on a monitor ofthe system of FIG. 1 during a modification of the scale of the synthesisimage;

FIGS. 8 and 9 illustrate examples of functions used by the viewingsystem of FIG. 1 during a transition from an image according to thefirst type of perspective to an image according to the second type ofperspective; and

FIG. 10 is a block diagram illustrating the implementation of a displaymethod according to one embodiment.

DETAILED DESCRIPTION

A first system 10 for viewing information related to a flight of anaircraft is diagrammatically illustrated by FIG. 1.

This system 10 is for example intended to be mounted in an aircraft, inparticular in a cockpit, intended for the crew of the aircraft, in thecabin, or intended for passengers of the aircraft. Alternatively, thesystem 10 may also be located on the ground, in particular in a groundstation, and can be intended for the preparation of missions or tocontrol an aircraft remotely from the ground station.

The system 10 comprises a central processing unit 12 and a displaydevice 14.

The display device 14 comprises a monitor 16 and means for processinggraphic information, for example a graphics processor and an associatedgraphics memory.

The graphics processor is suitable for processing graphic informationstored in the graphics memory and displaying that information or of adepiction thereof on the monitor 16.

The system 10 further comprises a man-machine interface 18 for theadjustment of parameters of the display on the display device 14 by anoperator, for example a member of the crew of the aircraft, a passenger,or a ground operator. The man-machine interface 18 for example comprisesa tactile control device, configured to detect the position of one ormore members, hereinafter called control members, on a surface of thattactile control device. In a known manner, these control members can bea stylus or the fingers of an operator.

Some tactile control device technologies make it possible to detect theposition of control members without there being contact between thecontrol member and the surface of the tactile control device.Subsequently, the expression “on” a surface or “on” a monitor must beunderstood as meaning “on or near” that surface or monitor.

In the next part of the description, we will consider an embodiment inwhich this tactile control device and the monitor 16 have a sharedshape, in the form of a touchscreen.

Thus, the man-machine interface 18 is configured to detect the positionof one or more members, hereinafter called control members, on thesurface of the monitor 16. In a known manner, these control members canbe a stylus or the fingers of an operator.

The central processing unit 12 is suitable for executing applicationsnecessary for the operation of the system 10.

To that end, the central processing unit 12 comprises a processor 24 andone or more memories 26.

The processor 24 is suitable for executing applications contained in thememory 26, in particular an operating system allowing the traditionaloperation of a computer system.

The memory 26 comprises different memory zones in particular containinga cartographical database 28, flight data 30 relative to a flight planof the aircraft, and applications intended to be executed by theprocessor 24.

The flight data 30 in particular comprises a planned trajectory for theaircraft, as well as a set of geographical points associated with theflight plan with which constraints can be associated, in particularaltitude, speed and time constraints, for example an altitude above,below or at which the aircraft must fly.

The memory 26 comprises an application 36 for dynamically generatingsynthesis images, also hereinafter called dynamic synthesis imagegenerating module or dynamic synthesis image generator 36, for theirdisplay by the display device 14.

The dynamic synthesis image generating module 36 is configured togenerate synthesis images representative of the environment situatednear the trajectory of the aircraft, and to control the display thereofby display viewing device 14. The module 36 is also configured to detectactions done by an operator, using the man-machine interface 18, tomodify generated synthesis images, in particular actions to modifyparameters of these images, and to generate modified synthesis images inresponse to such modification actions.

The module 36 is configured to generate synthesis images according to afirst type of perspective.

The synthesis images according to the first type of perspective arethree-dimensional synthesis images. The first type of perspective ispreferably a conical perspective, i.e., with a vanishing point.

As diagrammatically illustrated in FIG. 2, each synthesis imageaccording to the first type of perspective, denoted 38, comprises asynthetic depiction 42 of the environment situated in the vicinity ofthe trajectory of the aircraft, in particular of the terrain and itsrelief.

This depiction may comprise aeronautic data, such as airports and theirlanding strips and/or geographical references, such as cities, bodies ofwater (rivers, lakes, seas).

The synthesis images according to the first type of perspective caneither be egocentric, i.e., seen from a point of view corresponding tothe current position of the aircraft, for example a point of viewsituated in the cockpit of the aircraft, or exocentric, i.e., seen froma virtual camera, situated at a point other than the current position ofthe aircraft. In particular, an exocentric image can correspond to animage that would be seen by a virtual camera situated outside theaircraft and viewing the aircraft.

Subsequently, the point of view Pv will refer to the point in space fromwhich an image is seen. The position of this point of view Pvcorresponds to the position of the aforementioned virtual camera.

The module 36 is also configured to generate synthesis images accordingto a second type of perspective.

The synthesis images according to the second type of perspective are forexample images seen from an axonometric perspective, which has novanishing point and preserves the ratios between any length consideredin a direction in space and that same length measured in its depictionin the image. Such a perspective is also called cylindrical,orthographic, parallel or orthonormal perspective.

The synthesis images according to the second type of perspective are forexample vertical projection views, making it possible to view thevertical trajectory of the aircraft, and/or horizontal projection views,illustrating the horizontal trajectory of the aircraft.

An example of a synthesis image 39 a according to the second type ofperspective, in horizontal projection, i.e., seen from above, isillustrated in FIG. 3. Superimposed on this image is a synthesis image39 b according to the second type of perspective in vertical projection,i.e., seen from the side.

The visual impression of synthesis images according to an axonometricperspective seen from above or seen from the side comes much closer tothe visual impression of two-dimensional images seen from above or seenfrom the side, respectively. Thus, alternatively, the synthesis imagesaccording to the second type of perspective are real two-dimensionalimages, without depth.

Preferably, in the synthesis images according to the first and secondtypes of perspective, the vertical dimensions are shown on a largerscale than the horizontal dimensions. In particular, the terrain as wellas the objects shown in the synthesis images are resized by a predefinedfactor, for example three, along the vertical axis, so as to make thealtitude variations between the terrain, the aircraft and the differentobjects more easily perceptible by a user.

Each synthesis image is centered on a point hereinafter called thecentral point of interest Pc.

In particular, each synthesis image according to the first type ofperspective is centered on a central point of interest Pc situated at anobservation distance Z from the point of view Pv of the image.

The point of view Pv and the central point of interest Pc define adirection forming, with a horizontal plane, a viewing angle hereinaftercalled vertical angular position and denoted a_(V). In particular, azero vertical angular position is associated with the point of viewsituated in the horizontal plane containing the central point ofinterest Pc, and a negative vertical angular position is associated withthe point of view situated below the horizontal plane containing thecentral point of interest Pc, while a positive vertical angular positionis associated with the point of view situated above the horizontal planecontaining the central point of interest Pc.

The point of view Pv and the central point of interest Pc furthermoredefine a direction forming, with a predefined vertical plane, forexample a vertical plane tangent to the trajectory of the aircraft, aviewing angle hereinafter called horizontal angular position and denoteda_(h). In particular, a zero horizontal angular position is associatedwith a point of view situated upstream from a central point of interestPc in the direction of the trajectory, the direction formed between thepoint of view and the central point of interest being parallel to thevertical plane tangent to the trajectory of the aircraft. A horizontalangular position of less than 90 degrees in absolute value is associatedwith a point of view situated upstream from the central point ofinterest Pc in the direction of the trajectory, while a horizontalposition greater than 90 degrees in absolute value is associated with apoint of view situated downstream from the central point of interest Pcin the direction of the trajectory.

Each synthesis image according to the first type of perspectiverepresents an observation volume substantially corresponding to apyramid, hereinafter called observation pyramid, with a horizontalopening angle denoted a1 and a vertical opening angle denoted a2.

Each synthesis image according to the first type of perspectivetherefore represents a zone with length

${A\; 1} = {2Z\;{\tan\left( \frac{a\; 1}{2} \right)}}$and width

${A\; 2} = {2Z\;{{\tan\left( \frac{a\; 2}{2} \right)}.}}$The ratio between the length A1 and the width A2 is determined as afunction of the dimensions of the displayed image.

Indeed, the synthesis images are intended to be displayed on a window ofthe monitor 16, the length L_(f) and width l_(f) of which are preferablyfixed.

Each synthesis image according to the second type of perspective alsodepicts a zone with length A1 and width A2. In the images according tothe second type of perspective that are according to the side, the widthA2 in reality corresponds to the height of the depicted zone.

The synthesis images according to the second type of perspective depictthe environment using a given scale, which is defined as the ratiobetween the length L_(f) of the window in which the image is displayedand the actual length A1 of the zone depicted in that image. At aconstant length L_(f), the scale of an image according to the secondtype of perspective is therefore defined by the actual length A1 of thezone depicted in that image.

By extension, the “scale” of an image according to the first type ofperspective will refer to the ratio between the length L_(f) of thewindow in which the image is displayed and the quantity

$2Z\;{\tan\left( \frac{a\; 1}{2} \right)}$corresponding to the actual length A1 of the zone depicted in thatimage. With a constant horizontal opening angle, the scale of an imageaccording to the first type of perspective is therefore defined by thedistance Z between the point of view Pv and the central point ofinterest Pc.

In general, the apparent size of an object will henceforth refer to thesize of that object as displayed on the monitor, and the actual sizewill refer to its size relative to the environment.

Each synthesis image includes a scale indicator 40. This scale indicator40 is for example a disc with a constant apparent diameter. Thus, theactual diameter of this disc, relative to the depicted environment,varies as a function of the scale of the image.

Thus, the scale of a synthesis image according to the first type ofperspective or according to the second type of perspective is equal tothe ratio between the apparent diameter of the disc 40, which ispreferably constant, and the actual diameter of that disc, which variesas a function of the scale of the image.

Preferably, the actual value of the diameter or radius of this discrelative to the depicted environment is displayed, which allows a userto ascertain the depiction scale of the image. This disc 40 is centeredon the current position of the aircraft. Furthermore, the disc 40 ispreferably provided at its periphery with graduations 41 indicating aheading relative to the current position of the aircraft.

Each synthesis image further includes, when at least one portion of thetrajectory of the aircraft is included in the zone depicted in thesynthesis image, a curve 44 representative of this trajectory portion,this curve 44 being superimposed on the synthesis depiction of theenvironment.

Preferably, the trajectory portion is shown in the synthesis image inthe form of a ribbon. Such a form in particular allows a user toperceive the roll associated with each point of the trajectory.

The ribbon is for example a solid colored ribbon.

Furthermore, in the synthesis images according to the first type ofperspective, the actual width of this ribbon is for example constant.Thus, the apparent width of the ribbon displayed in the synthesis imageat a given point of the trajectory depends on the distance between thisgiven point and the point of view of the synthesis image, which allows auser to perceive this distance.

Preferably, an outline of the wireframe type is superimposed on thisribbon, for example in the form of two lines defining the width of theribbon, and the thickness of which is constant over the entire displayedimage. Such an outline makes it possible to make the trajectory visibleeven at points very remote from the point of view of the image.

Furthermore, the portion of the trajectory closest to the point of view,i.e., situated at a distance from the point of view of the image smallerthan a first predetermined threshold distance, can be done only by anoutline of the wireframe type. In this case, the colored ribbonpreferably has an increasing transparency from a point of the trajectorysituated at a second threshold distance from the point of view, greaterthan the first threshold distance, up to the point of the trajectorysituated at the first threshold distance, for which the ribbon iscompletely transparent. Such a transparency makes it possible to avoidoverloading the synthesis image.

Each synthesis image may also include symbolic objects. In particular,these objects are according to the first or second type of perspective,depending on whether the synthesis image is seen from the first orsecond type of perspective, respectively.

These symbolic objects are for example representative of the position ofpassage points, which may or may not be associated with constraints,altitude profile points associated with the trajectory of the aircraft,the position of the aircraft and/or objects that could interfere withthe trajectory of the aircraft, for example clouds, storm cells or otheraircraft.

A first symbolic object 46 illustrates a position of the aircraft alongthe trajectory. This generally involves the current position of theaircraft, or a future position of the aircraft, in the case of thedisplay of synthesis images representing a simulation of a flight or ofa particular flight phase of the aircraft.

The passage points comprise passage points associated with a verticalconstraint, for example an altitude above, below, or at which theaircraft must fly.

The altitude profile points are points specific to the trajectory of theaircraft corresponding to a change in flight phase. These points inparticular comprise a top of climb (TOC) point, which corresponds to thetransition point between the ascent phase and the cruising phase of theaircraft along the planned trajectory, a top of descent (TOD) point,from which the aircraft must begin its descent phase, and one or morebottom of step climb (BOSC) points.

Preferably, the three-dimensional shape of each symbolic objectaccording to the first type of perspective is chosen so as to be easilyrecognizable and distinguishable from the shapes of other symbolicobjects of different types, irrespective of the viewing angle from whichthe symbolic object is viewed. Furthermore, this three-dimensional shapemust also be chosen so as to be able to be displayed according to thesecond type of perspective without a loss of visual reference for user,in particular during a transition between an image according the firsttype of perspective and an image according to the second type ofperspective, while remaining recognizable when it is seen according tothe second type of perspective.

Furthermore, each symbolic object can be extended on the synthesisimages by a vertical line extending at ground level or up to apredetermined altitude, for example the current altitude of theaircraft. Furthermore, the images according to the first type ofperspective advantageously depict the shadows projected on each symbolicobject on the ground or on a predetermined altitude plane, which is forexample the current altitude of the aircraft. The vertical line and theshadow associated with each symbolic object make it possible to providethe user with an improved perception of the three-dimensional positionof that object.

The symbolic objects representative of passage points associated withaltitude constraints, seen from the side, differ from symbolic objectsrepresentative of passage points not associated with altitudeconstraints and altitude profile points. Furthermore, the symbolicobject representative of passage points associated with altitudeconstraints above, below, or at which the aircraft must fly,respectively, differ from one another seen from the side.

Thus, the passage points not associated with altitude constraints, thepassage points associated with altitude constraints above, below, or atwhich the aircraft must fly and the altitude profile points can bedistinguished from one another in the synthesis images according to thesecond type of perspective, seen from the side, illustrating thevertical trajectory of the aircraft.

Furthermore, seen from above, the symbolic objects representative ofpassage points differ from the symbolic objects representative ofaltitude profile points.

Thus, the passage points and the altitude profile points can bedistinguished from one another in synthesis images according to thesecond type of perspective, seen from above, illustrating the horizontaltrajectory of the aircraft.

As an example, FIG. 4 shows example depictions of symbolic objectsaccording to the first type of perspective, as well as the depiction ofthe same objects according to the second type of perspective, seen fromabove and from the side.

FIG. 4 thus shows a three-dimensional symbolic object 50 representativeof a passage point not associated with a constraint, according to thefirst type of perspective, as well as the depiction of that object seenfrom above 50 a and seen from the side 50 b according to the second typeof perspective.

FIG. 4 also shows three-dimensional symbolic objects 52, 54 and 56representative of passage points respectively associated with analtitude above which the aircraft must fly, an altitude below which theaircraft must fly, and an altitude at which the aircraft must fly,according to the first type of perspective, as well as depictions ofthese objects seen from above 52 a, 54 a, 56 a and seen from the side 52b, 54 b and 56 b, according to the second type of perspective.

FIG. 4 further illustrates a three-dimensional symbolic object 58representative of an altitude profile point, for example of the TOD, TOCor BOSC type, according the first type of perspective, as well asdepictions of this object seen from above 58 a and seen from the side 58b, according to the second type of perspective.

Furthermore, the three-dimensional shape according to the first type ofperspective of the symbolic object representative of the position of theaircraft and of other aircraft that may interfere with the trajectory ofthe aircraft, is chosen such that the orientation of the aircraft, seenfrom the side, is quickly detectable. Preferably, the vertical lineassociated with a symbolic object representative of the position of theaircraft extends to the current altitude of the aircraft, and the shadowof such an object is the shadow projected on a plane at the currentaltitude of the aircraft, which makes it possible to facilitate thecomparison between the current altitude of the aircraft and the altitudeof surrounding aircraft.

FIG. 5 thus shows a three-dimensional example depiction 60 according tothe first type of perspective of a symbolic object representative of theposition of an aircraft, with which a vertical line 62 and a projectedshadow 64 are associated. FIG. 5 also shows depictions of this objectseen from above 66 and from the side 68 according to the second type ofperspective.

Preferably, when another aircraft may interfere with the trajectory ofthe aircraft, the module 36 is configured to thicken and/or underlinethe affected portion of the trajectory, for example in red, asillustrated in FIG. 2 by reference 69.

Clouds and storms cells are depicted on the scale of the synthesisimages, in particular from weather information received from a weatherradar, in particular three-dimensional, positioned in the aircraft, orfrom a ground station.

As illustrated in FIG. 6, the clouds and storms cells are depicted inthe three-dimensional synthesis images according to the first type ofperspective in the form of colored three-dimensional masses 70, 72,respectively, which are preferably transparent, so as not to hide theobjects, in particular an aircraft, an altitude profile passage or atrajectory portion, located behind or within the cloud or storm cell.

Preferably, one or more sectional views 70 a, 72 a of the cloud or thestorm cell is/are superimposed on the associated three-dimensional massin order to allow the user to see the size and internal structure of thecloud or storm cell. As illustrated in FIG. 6, this for example involveshorizontal or vertical cross-sections, in a plane that intersects thetrajectory of the aircraft, and that can be adjusted by the user.

In the synthesis images according to the second type of perspective,clouds and storms cells are depicted in the form of a colored mass,preferably transparent.

Thus, the display in the synthesis images of objects representative ofclouds or storm cells makes it possible to identify potentialinterferences of the cloud or storm cell with the trajectory of theaircraft, and to modify the trajectory of the aircraft in order to avoidthem.

According to the first type of perspective, the apparent size of theobjects depends on the distance between those objects and the point ofview. Thus, the apparent size of these symbolic objects allows the userto see the distance of these objects, in particular the distance of thepoints, aircraft, clouds or storm cells depicted by these objects.

Preferably, when the distance between a symbolic object and the point ofview is comprised between a predetermined minimum distance and apredetermined maximum distance, the apparent size of the symbolic objectis a strictly decreasing function, for example linear, of the distancebetween the symbolic object and the point of view.

Furthermore, when the distance between the symbolic object and the pointof view is smaller than the predetermined minimum distance, the apparentsize of the object remains constant and equal to the apparent size thatthe symbolic object would have if the distance between the symbolicobject and the point of view was equal to the predetermined minimumdistance. Preferably, a transparency effect is also applied to theobject. This makes it possible to prevent an object very close to thepoint of view from concealing the field of vision.

Furthermore, when the distance between the symbolic object and the pointof view is larger than the predetermined maximum distance, the apparentsize of the object remains constant and equal to the apparent size thatthe symbolic object would have if the distance between the symbolicobject and the point of view was equal to the predetermined maximumdistance. This makes it possible to keep any object situated in thefield of vision visible, even if that object is very far from the pointof view.

The predetermined minimum and maximum distances are for exampleconfigurable and can be modified by user.

Thus, the module 36 is configured to apply a resizing factor to eachsymbolic object as a function of its distance from the point of view.This resizing factor is representative of the actual size of the objectrelative to the environment.

When the distance between a symbolic object and the point of view iscomprised between the predetermined minimum distance and thepredetermined maximum distance, the resizing factor is equal to 1, whichmeans that the object is depicted at its nominal size relative to theenvironment.

When the distance between the symbolic object and the point of view issmaller than the predetermined minimal distance, the resizing factor isless than 1, and is a strictly increasing function, for example linear,of the distance between the object and the point of view. Thus, whenthis distance decreases, the actual size of the object relative to theenvironment decreases.

When the distance between the symbolic object and the point of view isgreater than the predetermined maximum distance, the resizing factor isgreater than 1, and is a strictly increasing function, for examplelinear, of the distance between the object and the point of view. Thus,when this distance increases, the actual size of the object relative tothe environment increases.

When the distance between the symbolic object and the point of view issmaller than the predetermined minimum distance or larger than thepredetermined maximum distance, the resizing factor is for example equalto the ratio between the distance of the object from the point of viewand the predetermined minimum or maximum distance, respectively.

The synthesis images are thus generated by the module 36 as a functionof image parameters that in particular define:

-   -   the type of perspective of the image,    -   the position of the central point of interest Pc,    -   for images according to the first type of perspective, the        position of the point of view Pv, in particular its observation        distance Z from the central point of interest Pc, the horizontal        angular position a_(h) and the vertical angular position a_(v),        as well as the opening angles a1 and a2,    -   the scale of the image, which is defined, for images according        to the first type of perspective, by the observation distance Z,        and for images according to the second type of perspective, by        the actual length A1 of the zone depicted in these images.

Preferably, according to the first type of perspective, not allpositions of the point of view Pv are authorized. For example, thehorizontal and vertical angular positions are each comprised in apredefined authorized angular range. For example, the horizontal angularposition a_(h) is comprised between −90 degrees and 90 degrees, and thevertical angular position a_(v) is comprised between −15 degrees and 90degrees.

The indicated parameters may be defined by default.

In particular, the synthesis image may be seen by default according tothe first type of perspective.

Furthermore, the horizontal opening angle is for example set by defaultto 90 degrees, the vertical opening angle then being adapted as afunction of the length and width of the displayed image.

The vertical angular position a_(v) can also be determined by default,for example at a value of 30 degrees.

Furthermore, the observation distance Z between the central point ofinterest Pc and the point of view Pv can be set by default, inparticular such that a set of predetermined points, hereinafter calledset of points of interest, can be completely included in the observationpyramid. The module 36 is furthermore configured to automaticallydetermine an optimal position of the point of view Pv making it possibleto optimize the trajectory portion displayed in the image.

In particular, a distance Z₀ between the point of view Pv and thecentral point of interest Pc₀ being fixed, and a vertical angularposition a_(v0) being fixed, the module 36 is configured toautomatically determine a position of the point of view Pv, situated atthe distance Z₀ from the central point of interest Pc₀ and situated atthe vertical angular position a_(v0) making it possible to maximize theactual length of the trajectory portion viewed in the image, the openingangles a1 and a2 remaining fixed.

Furthermore, the vertical angular position a_(v0) is for example fixedat 30 degrees.

In order to determine an optimal horizontal angular position denoteda_(hopt), the module 36 is configured to determine a set of successivepoints on the trajectory, denoted Pi, according to a predeterminedsampling, from an initial point that for example corresponds to theposition of the aircraft, preferably in the downstream direction of thattrajectory. Indeed, the points of interest of the trajectory for anoperator are generally those which have not yet been reached by theaircraft.

For example, the points Pi are regularly spaced apart on the trajectory.

The module 36 is further configured to determine an optimal verticalangular position making it possible to optimize the number of points Piincluded in the viewing pyramid, the points Pi of the trajectory closestto the initial point having priority relative to the points Pi of thetrajectory further from the initial point.

For example, the module 36 is configured to successively adjust theangular position, from a starting horizontal angular position a_(h0), soas to successively include the points Pi in the viewing pyramid, whilekeeping all of the points of interest within the observation pyramid.

To that end, the module 36 is configured to iteratively carry outsuccessive phases for determining a modified horizontal angular positiona_(hi) so as to successively include, in the observation pyramid,successive points of the trajectory Pi.

Thus, during the first of these iterative phases, the module 36 isconfigured to determine a first modified horizontal angular positiona_(h1). To that end, the module 36 is configured to determine a modifiedhorizontal angular position such that the point P₁ is included in theobservation pyramid, preferably so that the edge of the observationpyramid closest to the point P₁ before modification of the initialhorizontal angular position a_(h0) intersects the point P₁ when thehorizontal position is equal to that modified horizontal angularposition.

If this modified horizontal angular position is not comprised in thepredefined authorized angular range for the horizontal position, forexample not comprised between −90 degrees and 90 degrees, the module 36is able to choose, as first modified horizontal angular position a_(h1),the boundary of that authorized range closest to the modified horizontalangular position thus determined.

If the modified horizontal angular position is comprised in the secondpredefined authorized angular range for the horizontal angular position,the module 36 is able to choose this first modified angular position asfirst modified horizontal angular position a_(h1).

Then, during the following phase, the module 36 is configured todetermine a modified horizontal angular position a_(hi). To that end,the module 36 is configured to determine a modified horizontal angularposition such that the point P_(i) is included in the observationpyramid, preferably so that the edge of the observation pyramid closestto the point P_(i) before modification of the modified horizontalangular position a_(hi-1) determined during the preceding iterationintersects the point P_(i) when the horizontal angular position is equalto that modified horizontal angular position.

Likewise, if the modified horizontal angular position is not comprisedin the predefined authorized angular range for the horizontal angularposition, the module 36 is able to choose the boundary of thisauthorized range closest to the determined angular position as the newmodified horizontal angular position a_(hi).

If the modified horizontal angular position is comprised in thepredefined authorized angular range for the horizontal angular position,the module 36 is able to choose this modified angular position as newmodified horizontal angular position a_(vi).

In each phase, the module 36 is configured to end the sequence ofiterations if, during that iteration, it is not possible to find ahorizontal angular position such that the considered point Pi of thetrajectory is included in the observation pyramid without other pointsP₁, . . . , P_(i-1) of the trajectory or points of the set of points ofinterest leaving the observation pyramid.

The optimal horizontal angular position a_(hopt) is then chosen by themodule 36 as the last determined modified angular position a_(hi-1).

The image parameters can also be set by an operator, by actions tomodify the displayed synthesis image performed via the man-machineinterface 18.

Such modification actions are performed by an operator, through theman-machine interface 18.

These modification actions can in particular consist of an action tomodify the perspective of the synthesis image, an action to modify theposition of the point of view, an action to modify the central point ofinterest, or an action to modify the scale of the image, whichcorresponds, in the case of an image according to the first type ofperspective, to a modification of the observation distance between thepoint of view and the central point of interest, or in the case of animage according to the second type of perspective, a modification of theactual size of the illustrated zone.

The module 36 is configured to detect such modification actions, and togenerate modified synthesis images in response to such modificationactions.

In order to facilitate the performance of some of these actions by anoperator, the generating module 36 is able to superimpose, on thesynthesis objects, one or more objects each associated with a specificmodification action, and each indicating a zone of the image in whichthe modification action must be performed, as described below.

In particular, the module 36 is able to display, on each synthesisimage, an icon 80 forming an activatable button, the actuation of whichis intended to modify the central point of interest of the image, inorder to use the current position of the aircraft as new central pointof interest.

This actuation is done using the man-machine interface 18, for exampleby positioning a control member on the zone of the touchscreen 16displaying the icon 80. The icon 80 is for example in the general shapeof the aircraft.

The module 36 is configured to detect a modification action of thecentral point of interest, in order to go from an initial image centeredon an initial central point of interest Pc₀ to a final image centered ona final modified central point of interest Pc_(n).

The module 36 is configured to determine the final modified centralpoint of interest Pc_(n) as a function of the detected modificationaction. Furthermore, the module 36 is configured to generate a finalmodified synthesis image centered on the final modified central point ofinterest Pc_(n) and to command the display thereof by the display device14.

Preferably, the modification of the central point of interest is donewithout modifying the distance Z between the point of view and thecentral point of interest. Such a modification therefore generally alsoresults in modifying the position of the point of view. The finalmodified synthesis image is then seen from a modified point of viewPv_(n) different from the point of view Pv₀ of the initial image.Furthermore, this modification of the central point of interest is forexample done without modifying the viewing angles a₁ and a₂.

Furthermore, the module 36 is configured to generate, at a plurality ofsuccessive transition moments, a transition image between the initialimage and the final image, in order to display these successivetransition images, then the final image. Each transition image generatedat a given transition moment is centered on an intermediate centralpoint of interest Pc_(i) situated between the initial central point ofinterest Pc₀ and the final modified central point Pc_(n) and seen from amodified point of view Pv_(i) situated between the initial point of viewPv₀ and the final point of view Pv_(n). The module 36 is furtherconfigured to control the successive display of the transition images ata plurality of moments between the display moment of the initial imageand the display moment of the final image.

An action to modify the central point of interest may be of severaltypes.

The first type of action to modify the central point of interestcomprises actuating the icon 80, in order to center the synthesis imageon the current position of the aircraft.

A second type of modification of the central point of interest consistsof selecting any targeted point of the synthesis image via theman-machine interface 18, in order to choose that point as central pointof interest. This selection is for example done by positioning a controlmember on the touchscreen 16 across from the targeted point.

The module 36 is configured to detect an action to modify the centralpoint of interest of the first or second type and centered on theposition of the aircraft or on the targeted point, to determine thefinal modified central point of interest Pc_(n) as a function of thedetected modification action, to generate a final modified synthesisimage centered on the final modified central point of interest Pc_(n)and to command the display thereof by the viewing device 14.Furthermore, as described above, the module 36 is configured togenerate, at a plurality of successive transition moments, transitionimages, and to command the successive display of these transition imagesat a plurality of moments between the display moment of the initialimage and the display moment of the final image.

A third type of action to modify the central point of interest comprisesa movement of a member by an operator between an initial position and afinal position.

For example, this member is a control member, and the third type ofmodification action of the central point of interest comprises amovement of this control member by an operator between an initialposition and a final position on the touchscreen 16.

According to a first embodiment, such a movement is intended to cause acorresponding movement of the central point of interest on the synthesisimage.

According to a second embodiment, such a movement is intended to drive amovement of the central point of interest on the synthesis image alongthe trajectory of the aircraft. According to the second embodiment, thecentral point of interest remains along the trajectory independentlyfrom the modification action, in particular from the movement of themember by the operator, in particular when this movement is done in adirection not parallel, therefore secant, to the tangent to thetrajectory curve at the initial central point of interest.

The choice of the first or second mode may for example be made by anoperator via the man-machine interface 18.

When the first or second mode is activated, the module 36 is configuredto detect a movement of a member between an initial position and a finalposition, in particular a movement of the control member by an operatoron the touch screen 16 between an initial position and a final position.

The module 36 is configured to detect, at each moment during thismovement, an intermediate position of the member comprised between itsinitial position and its final position, as well as an intermediatemovement vector between the initial position and the intermediateposition. At the end of the movement of the member by the operator, themodule 36 is configured to determine a final movement vector of themember between its initial position and its final position.

When the first mode is activated, the module 36 is configured todetermine, at each moment, during the movement of the member, atranslation vector for the central point of interest as a function ofthe movement of the member between its initial position and itsintermediate position at that moment and to determine an intermediatemodified central point of interest Pc_(i), by applying the movementvector to the initial central point of interest Pc₀.

For example, the translation vector for the central point of interest isdetermined at each moment as a component in a horizontal plane of thesynthesis image of the movement vector of the member between its initialposition and its intermediate position.

The module 36 is further configured to determine a final translationvector for the central point of interest as a function of the finalmovement vector and to determine a final modified central point ofinterest Pc_(n), by applying the final movement vector to the initialcentral point of interest Pc₀.

The final translation vector is for example determined as the componentin a horizontal plane of the synthesis image of the final movementvector of the member between its initial position and its finalposition.

When the second mode is activated, the synthesis image is centered bydefault on a central point of interest situated along the curve 44representative of the trajectory of the aircraft. The initial centralpoint of interest is therefore situated along this trajectory curve.

When the second mode is activated, the module 36 is configured todetermine, at each moment, during the movement of the member, anintermediate modified central point of interest Pc_(i) that is situatedalong the curve representative of the trajectory of the aircraft,whatever the movement of the member between its initial position and itsintermediate position.

Furthermore, the module 36 is configured to determine, as a function ofthe modification action, a final modified central point of interest thatis situated along the curve representative of the trajectory of theaircraft, whatever the movement of the member between its initialposition and its final position.

The second mode thus allows an operator to modify the central point ofinterest while remaining along the trajectory of the aircraft, and thusto view the terrain situated along that trajectory, without it beingnecessary for the operator to move the member in a directioncorresponding, at each moment, to the direction of the trajectory.

In particular, the module 36 is configured to determine, at each momentduring the modification action, from the movement vector of the memberbetween its initial position and its intermediate position, thecomponent of that vector in a horizontal plane of the synthesis image.The module 36 is further configured to determine, at each moment, fromthis horizontal component, a curvilinear distance on the trajectorycurve between the initial central point of interest Pc₀ and anintermediate modified central point of interest Pc_(i), then todetermine an intermediate modified central point of interest Pc, byapplying, to the initial central point of interest Pc₀, a movement alongthe trajectory curve 44 by a length equal to the curvilinear distancethus determined.

For example, the curvilinear distance is determined as a function of thehorizontal component of the movement vector and a vector tangent to thecurve at the initial central point of interest, in particular as afunction of a scalar product between the horizontal component and thetangent vector.

At the end of the movement of the member by the operator, the module 36is configured to determine, from the final movement vector of the memberbetween its initial position and its final position, the component ofthis final movement vector in a horizontal plane of the synthesis image.The module 36 is further configured to determine, from this horizontalcomponent, a curvilinear distance on the trajectory curve between theinitial central point of interest Pc₀ and the final modified centralpoint of interest Pc_(n), then to determine the final modified centralpoint of interest Pc_(n) by applying, to the initial central point ofinterest, a movement along the trajectory curve by a length equal to thecurvilinear distance thus determined.

According to the first and second modes, the module 36 is configured togenerate, at each moment, an intermediate modified synthesis imagecentered on the intermediate modified central point of interest Pc_(i)determined at that moment and to command the display thereof by thedisplay device 14. The module 36 is also configured to generate, at theend of the movement, a final modified synthesis image centered on thefinal modified central point of interest Pc_(n) and to command thedisplay thereof by the display device 14.

Preferably, at the end of the movement of the member by the operator,the module 36 is configured to virtually extend this movement in orderto add an inertia effect to the movement of the member by the operator.The module 36 is thus configured to determine one or more additionalmodified synthesis images intended to be displayed after the finalmodified synthesis image, each centered on an additional modifiedcentral point of interest determined based on a virtual movement beyondthe actual final position of the member at the end of its movement.

The generating module 36 is further configured to display, in thesynthesis images according to the first type of perspective, an icon 82forming a vertical slide or an icon 84 forming a horizontal slide.

The vertical slide 82 is associated with an action to modify the viewingangle in a vertical plane, i.e., an action to modify the position of thepoint of view of the image, this modification being a rotation of thepoint of view relative to the central point of interest in the verticalplane containing the initial point of view and the central point ofinterest, i.e., a modification of the vertical angular position a_(v) ofthe point of view.

This action to modify the vertical angular position a_(v) is done usingthe man-machine interface 18, for example by moving a control memberover the zone of the touchscreen 16 displaying the vertical slide 82from top to bottom or from bottom to top along the vertical slide 82.

In particular, a movement from top to bottom along the vertical slide 82can cause a rotation of the position of the point of view toward thebottom of the image, while a movement from bottom to top along thevertical slide 82 is able to cause a rotation of the position of thepoint of view toward the top of the image.

The vertical slide 82 extends substantially vertically in the synthesisimage between an upper stop 82 a and a lower stop 82 b, which are forexample associated with the boundaries of the range authorized for thevertical angular position a_(v). For example, the upper stop 82 a isassociated with a vertical angular position a_(v) of 90 degrees, whilethe lower stop 82 b is associated with a vertical angular position a_(v)of −15 degrees.

The horizontal slide 84 is associated with an action to modify theviewing angle in a horizontal plane, i.e., an action to modify theposition of the point of view of the image, this modification being arotation of the point of view relative to the central point of interestin the horizontal plane containing the initial point of view and thecentral point of interest, i.e., a modification of the horizontalangular position a_(h) of the point of view.

This action to modify the horizontal angular position a_(h) is doneusing the man-machine interface 18, for example by moving a controlmember over the zone of the touchscreen 16 displaying the horizontalslide 84 from left to right or from right to left along the horizontalslide 84.

In particular, a movement from left to right along the horizontal slide84 can cause a rotation of the position of the point of view in thecounterclockwise direction, while a movement from right to left alongthe horizontal slide 84 can cause a rotation of the position of thepoint of view in the clockwise position.

The horizontal slide 84 extends substantially horizontally over thesynthesis image between a left stop 84 a and a right stop 84 b, whichare for example associated with the boundaries of the range authorizedfor the horizontal angular position a_(h). For example, the left stop 84a is associated with a horizontal angular position a_(h) of −90 degrees,while the right stop 84 b is associated with a horizontal angularposition a_(h) of 90 degrees.

Preferably, when no control member is positioned on the touchscreen 16in the zone displaying the slide 82, the slides 82 and 84 are displayedtransparently only. This makes it possible to avoid overloading thesynthesis images with the slides 82 and 84 when their display is notnecessary.

Furthermore, as long as a positioning of a control member on thetouchscreen 16 in the zone displaying the vertical slide 82 orhorizontal slide 84 is detected, the module 36 is able to superimpose,on the vertical 82 or horizontal 84 slide, respectively, a markerindicating the current position of the control member on the zonedisplaying the slide 82 or 84. This marker is for example a horizontalor vertical line intersecting the vertical 82 or horizontal 84 slide,respectively.

The vertical 82 and horizontal 84 slides are each associated with apredetermined rotation scale. In particular, a given position along thevertical slide 82, along the horizontal slide 84, respectively, isassociated with a given vertical angular position a_(v), a givenhorizontal angular position a_(h), respectively.

The module 36 is configured to detect an action to modify the viewingangle in a horizontal or vertical plane, and to determine in real time,at each moment during this movement, a modified horizontal or verticalangular position as a function of the position of the member on theslide 82 or 84. The module 36 is further configured to determine amodified point of view at the horizontal or vertical angular position asmodified, and to generate a modified synthesis image seen from themodified point of view thus determined.

The module 36 is further configured to detect an action to modify thescale of the image.

A scale modification action corresponds, for the images according to thefirst type of perspective, to a modification of the observation distanceZ between the point of view Pv and the central point of interest Pc. Forthe images according to the second type of perspective, a scalemodification action corresponds to a modification of the actual size ofthe depicted zone, i.e., a modification of the length A1 andconsequently of the width A2 of the depicted zone.

In particular, an action to increase the scale of the synthesis imagecorresponds, for the images according to the first type of perspective,to a decrease in the observation distance Z, and for the imagesaccording to the second type of perspective, to a decrease in the lengthA1 and width A2 of the illustrated zone.

Conversely, an action to reduce the scale of the synthesis imagecorresponds, for the images according to the first type of perspective,to an increase of the observation distance Z, and for the imagesaccording to the second type of perspective, to an increase of thelength A1 and width A2 of the depicted zone.

The module 36 is further configured to generate, in response to such amodification action, modified synthesis images, and to command thedisplay of these modified synthesis images on the display device 14.

A scale modification action is performed by a user using the man-machineinterface 18. In particular, such a modification action comprises amovement of two control members on the touchscreen 16 in twosubstantially opposite directions, which can be followed by maintenanceof the two control members on the touchscreen 16 at the end of theirmovement.

The module 36 is configured to detect the position, at an initialmoment, of two control members on the touchscreen 16 in two initialpositions associated with two distinct initial points P₁ and P₂, anddetermine, when this positioning is detected, a midpoint P_(m) situatedmidway between these two initial points, as well as a first zone 98, asecond zone 100 and a third zone 102 centered on this midpoint.

As illustrated in FIG. 7, the first, second and third zones 98, 100, 102are defined by two closed curves C₁, C₂ centered on the midpoint P.

In the illustrated example, the two closed curves C₁, C₂ are each in theshape of a square whereof one of the diagonals passes through the twoinitial points P₁ and P₂. Alternatively, the two curves C₁, C₂ arepolygonal, round or oval, or have any curved shape. Each of these curvesC₁, C₂ defines a set of points situated inside these curves. The twoinitial points P₁ and P₂ are comprised in the set of points defined bythe second curve C₂, but not comprised in the set of points defined bythe first curve C₁.

The first zone 98, which includes the initial points P₁ and P₂, isformed by the set of points contained between the first curve C₁ and thesecond curve C₂.

The second zone 100 is formed by the set of points contained inside thesecond curve C₂. This second zone 100 is associated with a scalereduction action, as described below.

The third zone 102 is formed by points situated outside the curves C₁and C₂. This third zone 102 is associated with a scale increase action,as described below.

A scale increase action of the synthesis image comprises a movement ofthe two control members on the touchscreen 16 following a substantiallyrectilinear trajectory in two substantially opposite directions awayfrom one another, optionally followed by maintenance of the two controlmembers on the touchscreen 16 following their movement.

In reference to FIG. 7, such a scale increase action comprises amovement of two control members from the initial points P₁ and P₂ in twoopposite directions B, B′ away from the midpoint P_(m). A scale increaseaction therefore corresponds to an increase in the distance d betweenthe two members.

A scale decrease action of the synthesis image comprises a movement ofthe two members on the touchscreen 16 following a substantiallyrectilinear trajectory in two substantially opposite directions towardone another, optionally followed by maintenance of the two controlmembers on the touchscreen 16 following their movement.

In reference to FIG. 7, such a scale decrease action comprises amovement of two control members from the initial points P₁ and P₂ in twoopposite directions C, C′ toward the midpoint P_(m). A scale decreaseaction therefore corresponds to a decrease in the distance d between thetwo control members.

The module 36 is able to detect the movements of the two control membersand to determine, at each moment, as a function of the position of thesecontrol members, a resizing factor of the initial image, hereinaftercalled scale modification factor of the image.

This scale modification factor, denoted γ, is defined as amultiplicative factor designed to be applied to a perimeter of theinitial image in order to determine a modified parameter associated witha modified scale.

For example, for the synthesis images according to the first type ofperspective, a scale multiplication by the factor γ corresponds to amultiplication of the observation distance of the factor γ to determinea modified observation distance.

For the synthesis images according to the second type of perspective, amultiplication of the scale by the factor γ corresponds to amultiplication of the length A₁ and the width A₂ of the zone depicted bythe image by a factor γ.

During a scale decrease, the scale modification factor is strictlygreater than 1.

During a scale increase, the scale modification factor is strictlycomprised between 0 and 1.

The module 36 is configured to determine, at each moment, denoted ti,the scale modification factor γ_(i) as a function of the position of thecontrol members relative to the first zone 98.

In particular, the module 36 is configured to determine the scalemodification factor according to a first computation mode while thecontrol members remain positioned on the touchscreen 16 across frompoints situated inside the first zone 98, and to determine thepositioning factor according to a second computation mode when thecontrol members are positioned on the touchscreen 16 across from pointssituated outside the first zone 98, i.e., inside the second zone 100 orthe third zone 102.

While the control members remain positioned on the touchscreen 16 acrossfrom points situated inside the first zone 98, the module 36 determines,at each moment, the scale modification factor γ_(i) as a function of thedistance between these control members at that moment and the distancebetween the initial points P₁ and P₂. Preferably, the scale modificationfactor γ_(i) is a strictly decreasing function of the distance d_(i)between the control members, for example a linear function of thedeviation or the ratio between the distance d0 between the initialpoints P₁ and P₂ and the distance d_(i) between the control members atthat moment.

As an example, the scale modification factor γ_(i) is determinedaccording to a formula of the type:

${\gamma_{i} = {k\;\frac{d_{0}}{d_{i}}}},$where k is a strictly positive proportionality factor.

When the control members are positioned on the touchscreen 16 acrossfrom points situated outside the first zone 98, the module 36determines, at each moment t′i, the scale modification factor, denotedγ′_(i), as a function of the maintenance duration of the control membersoutside the first zone 98. This maintenance duration, denoted Ti,corresponds to the length of time elapsed between the moment denoted t′₀at which one or two control members have reached the boundaries of thefirst zone 98 and the moment t′i under consideration.

Preferably, as long as the control members are positioned on thetouchscreen 16 across from points situated outside the first zone 98,the scale modification factor γ′_(i) is independent of the position ofthe points of the screen situated across from these control members.

At the moment t′₀, the scale modification factor γ′₀ is equal to thescale modification factor determined according to the first computationmode.

The scale modification factor is then a strictly monotonous function ofthe maintenance duration Ti.

In particular, if the control members are positioned on the touchscreen16 across from points situated inside the second zone 100, the scalemodification factor is a strictly increasing function of the maintenanceduration Ti.

Conversely, if the control members are positioned on the touchscreen 16across from points situated inside the third zone 102, the scalemodification factor is a strictly decreasing function of the maintenanceduration Ti.

Thus, when the control members are situated in the second zone 100 or inthe third zone 102, the mere maintenance of the control members on thetouchscreen 16 makes it possible to continue the scale decrease orincrease action, respectively. It is thus possible for a user to resizethe zone depicted by the image by the desired scale modification factorwithout it being necessary, due to the finite dimensions of thetouchscreen 16, to perform several successive modification actions.

Preferably, the absolute value of the drift of the scale modificationfactor γ′_(i) is an increasing function over time, which means that thescale change occurs more and more quickly when the maintenance durationTi increases. This in particular makes it possible to go quickly fromthe city scale to the country or continent scale, or conversely to goquickly from the continent scale to the country or city scale, in asingle gesture.

In particular, when the control members are positioned on thetouchscreen 16 across from points situated in the second zone 100, thescale modification factor γ′_(i) is a convex function, in particularstrictly convex, of the maintenance duration Ti. For example, the scalemodification factor γ′_(i) increases exponentially when the maintenanceduration Ti increases. According to another example, the scalemodification factor γ′_(i) is a piecewise affine function, the slope ofthe affine function, which is positive, increasing when the maintenanceduration Ti increases.

When the control members are positioned on the touchscreen 16 acrossfrom points situated in the third zone 102, the scale modificationfactor γ′_(i) is a concave function, in particular strictly concave, ofthe maintenance time Ti. For example, the scale modification factorγ′_(i) decreases exponentially when the maintenance duration Tiincreases. According to another example, the scale modification factorγ′_(i) is a piecewise affine function, the slope of the affine function,which is negative, decreasing when the maintenance duration Tiincreases.

As indicated above, the module 36 is configured to detect a scalemodification action and to determine, at each of a plurality ofsuccessive moments during such an action, a scale modification factorγ_(i) or γ′_(i).

Preferably, a minimum scale modification factor and a maximum scalemodification factor are predetermined. When the scale modificationfactor γ_(i) or γ′_(i) reaches the minimum or maximum scale modificationfactor, the scale modification factor γ_(i) or γ′_(i) remains equal tothe minimum or maximum scale modification factor, respectively, even ifthe distance d_(i) between the control members increases or decreasesrespectively, and even if the control members remain positioned on thetouchscreen 16 across from points situated in the second or third zone.

Furthermore, the module 36 is configured to apply, at each of thesuccessive moments, the scale modification factor γ_(i) or γ′_(i)determined at that moment to the scale of the initial synthesis image todetermine a modified scale.

In particular, according to the second type of perspective, amultiplication of the scale of the initial image by the scalemodification factor corresponds to a multiplication of the length A1 andthe width A2 of the zone depicted by the image by a factor γ. Accordingto the first type of perspective, a multiplication of the scale of theinitial image by the scale modification factor corresponds, with a fixedopening angle, to a modification of the distance Z between the point ofview and the central point of interest by the factor γ.

The module 36 is further configured to generate, at each of thesemoments, a modified image with a modified scale thus determined, and tocommand the display thereof on the display device 14.

Preferably, when the modification action corresponds to a scaleincrease, the modified image has the midpoint P_(m) as central point ofinterest. Alternatively, the modified image keeps the same central pointof interest as the initial image.

Likewise, when the modification action corresponds to a scale decrease,the modified image for example has the midpoint P_(m) as central pointof interest. Alternatively, the modified image keeps the same centralpoint of interest as the initial image.

Once the control members are no longer positioned on the touchscreen 16,the scale modification action of the synthesis image stops.

Preferably, the module 36 is configured to compare the dimensions A_(1n)and A_(2n) or the distance Zn associated with the last generatedmodified image to predetermined dimension or distance threshold, and todetermine the dimension thresholds, the distance threshold,respectively, closest to the dimensions A_(1n) and A_(2n) or thedistance Z_(n).

The module 36 is further configured to generate a final modified imagedepicting a zone whereof the dimensions correspond to the closestdetermined dimension thresholds and/or a distance Z equal to thedetermined distance threshold, and to command the display thereof on thedisplay device 14. Thus, the observation distance Z or the dimensions ofthe depicted zone to magnetize themselves over an observation distanceor predefined dimensions.

The module 36 is further configured to detect a modification action ofthe image type of perspective, for example, an action to go from animage according to the first type of perspective to an image accordingto the second type of perspective, in particular seen from above or seenfrom the side, or an action to go from an image according to the secondtype of perspective to an image according to the first type ofperspective. The passage from an image according to the first type ofperspective to an image according to the second type of perspective isfor example desirable when the operator, for example the pilot, wishesto modify the flight plan, in particular one or several passage pointsof the flight plan. A view according to the second type of perspective,from above or the side, is in fact more appropriate for such amodification than a view according to the first type of perspective.

This modification action is done using the man-machine interface 18, forexample by actuating a dedicated icon superimposed on the synthesisimage by the module 36.

According to one example, an action to go from a synthesis imageaccording to the first type of perspective to a synthesis imageaccording to the second type of perspective seen from above comprises amovement of the control member over the zone of the touchscreen 16displaying the vertical slide 82 from bottom to top along that verticalslide 82 up to the upper stop 82 a.

According to this example, the synthesis image according the first typeof perspective, hereinafter called initial synthesis image, from whichthe transition toward the synthesis image according to the second typeof perspective is done, is preferably seen from a point of view having avertical angular position equal to 90 degrees. This is therefore animage according to the first type of perspective seen from above.

The module 36 is configured to detect a modification action aiming to gofrom a synthesis image according to the first type of perspective to asynthesis image according to the second type of perspective or from asynthesis image according to the second type of perspective to asynthesis image according to the first type of perspective, and togenerate, in response to such an action, a plurality of successivethree-dimensional transition images between the synthesis imageaccording the first type of perspective and the synthesis imageaccording to the second type of perspective or between the synthesisimage according to the second type of perspective and the synthesisimage according the first type of perspective, respectively.

The transition images are synthesis images according to the first typeof perspective.

The image according to the second type of perspective is for example animage seen from above.

The transition images are intended to be displayed on the display device14 at a plurality of successive transition moments, between an initialdisplay moment of the synthesis image according to the first type ofperspective or according to the second type of perspective,respectively, and a final display moment of the synthesis imageaccording to the second type of perspective or according to the firsttype of perspective, respectively.

The transition images are intended to ensure a continuous and fluidtransition between the synthesis image according to the first type ofperspective and the synthesis image according to the second type ofperspective or between the synthesis image according to the second typeof perspective and the synthesis image according to the first type ofperspective, respectively.

Each transition image is centered around a central point of interestPci, hereinafter called intermediate central point of interest, is seenfrom a point of view Pvi hereinafter called intermediate point of view,the observation distance Zi between this intermediate point of view andthe intermediate central point of interest being called intermediateobservation distance, and is seen from an intermediate horizontalopening angle a1 i and a vertical intermediate opening angle a2 i.

Each transition image shows a zone of the environment with length A1 i,called intermediate length, and width A2 i, called intermediate width,the ratio between the intermediate length A1 i and the intermediatewidth A2 i remaining constant and equal to the ratio between the lengthA1 and the width A2 of the three-dimensional synthesis image. Thehorizontal a1 i and vertical a2 i intermediate opening angles beinglinked to one another as a function of the ratio between theintermediate length A1 i and the intermediate width A2 i that remainsconstant, “opening angle” will hereinafter generally refer to one or theother of these opening angles, for example the intermediate horizontalopening angle a1 i.

During a transition between the initial synthesis image according to thefirst type of perspective and a final synthesis image according to thesecond type of perspective, the module 36 is configured to generatethree-dimensional transition images according to the first type ofperspective by decreasing, from one transition image to the next, theopening angle a1 i, and increasing, from one transition image to thenext, the observation distance Zi, such that the length A1 i of the zonerepresented by each transition image remains comprised in a predefinedbounded interval around the length A1 of the zone shown by the initialsynthesis image. The initial synthesis image can itself be considered atransition image.

The decrease of the opening angle a1 i from one transition image to thenext makes it possible to achieve a fluid transition between thesynthesis image according the first type of perspective and thesynthesis image according to the second type of perspective. Inparticular, the visual gap between a three-dimensional image accordingto the first type of perspective seen with a very small opening angle a1i, for example 5°, and the corresponding image according to the secondtype of perspective is practically imperceptible.

Furthermore, the increase in the observation distance Zi makes itpossible to keep a zone length depicted by the transition imagessubstantially identical to the length of the zone represented by theinitial synthesis image and therefore contributes to providing a fluidtransition between the initial synthesis image according to the firsttype of perspective and the final synthesis image according to thesecond type of perspective.

The module 36 is thus configured to determine, for each transitionimage, the intermediate opening angle a1 i and the intermediateobservation distance Zi of that transition image.

The intermediate opening angle a1 i of each transition image is smallerthan the opening angle a1 of the initial synthesis image and theintermediate opening angle of any preceding transition image.

The opening angle a1 i of each transition image is thus a decreasingfraction of the transition moment at which that transition image isintended to be displayed.

“Decreasing function” refers to a non-constant decreasing function,i.e., as at least one first and one second successive transition momentexist, the second transition moment ti being after the first transitionmoment t_(i-1), such that the intermediate opening angle a1 _(i-1) of afirst transition image intended to be displayed at the first moment isstrictly smaller than the intermediate opening angle a1 i of a secondtransition image intended to be displayed at the second transitionmoment.

The intermediate opening angle a1 i of each transition image ispreferably strictly smaller than the opening angle a1 of the initialsynthesis image and the intermediate opening angle of any precedingtransition image.

The opening angle a1 i of each transition image is then a strictlydecreasing function of the transition moment at which that transitionimage is intended to be displayed.

For example, the opening angle of the initial synthesis image iscomprised between 30° and 140°, in particular equal to 90°, and theintermediate opening angle of the last transition image is smaller than10°, for example comprised between 0.1° and 10°, for examplesubstantially equal to 5°.

The intermediate observation distance Zi of each transition image isgreater than the observation distance Z of the initial synthesis imageand the intermediate observation distance of any preceding transitionimage.

The intermediate observation distance Zi of each transition image isthus an increasing function of the transition moment at which thattransition image is intended to be displayed.

“Increasing function” refers to a non-constant increasing function,i.e., as at least one first and one second successive transition momentexist, the second transition moment ti being after the first transitionmoment t_(i-1), such that the intermediate observation distance Z_(i-1)of a first transition image intended to be displayed at the first momentis strictly greater than the intermediate observation distance Zi of asecond transition image intended to be displayed at the secondtransition moment.

The intermediate observation distance Zi of each transition image ispreferably strictly greater than the observation distance Z of theinitial synthesis image and the intermediate observation distance of anypreceding transition image.

The intermediate observation distance Zi of each transition image isthen a strictly increasing function of the transition moment at whichthat transition image is intended to be displayed.

For example, the observation distance of the initial synthesis image isequal to 100 m, and the observation distance of the last transitionimage is substantially equal to 1600 km.

Preferably, the intermediate observation distance Zi of each transitionimage is a nonlinear increasing function, in particular convex, of thetransition moment at which that transition image is intended to bedisplayed.

In particular, such a convex function makes it possible to make thetransition between the initial image and the final image more fluid.

FIG. 8 shows an example function linking the transition moment ti, onthe x-axis, to the intermediate observation distance Zi, on the y-axis,the scales on the x-axis and y-axis being normalized between 0 and 1.

Furthermore, the module 36 is preferably configured to determine theintermediate opening angle a1 i of each transition image as a functionof the intermediate observation distance Zi determined for thattransition image.

Preferably, the intermediate opening angle a1 i of each transition imageis a nonlinear decreasing function of the transition moment ti at whichthat transition image is intended to be displayed.

In particular, the intermediate opening angle a1 i of a transition imageis determined as a function of the intermediate observation distance Zisuch that the length of the zone depicted by the transition image iscomprised in a predetermined bounded interval around the length A1 ofthe zone depicted by the initial synthesis image.

For example, the intermediate opening angle a1 i of each transitionimage is determined as a function of the opening angle a1 of the initialsynthesis image, a virtual opening angle a1′i and the transition momentti at which the transition image is intended to be displayed.

The virtual opening angle a1′i is such that the length of the zonedepicted in a virtual image seen from an observation distance equal tothe intermediate observation distance Zi of the transition image andseen with that virtual opening angle a1′i would be equal to the lengthA1 of the zone depicted by the initial synthesis image.

The virtual opening angle a1′i is thus equal to:

${a\; 1_{i}^{\prime}} = {2*{\arctan\left( \frac{A\; 1}{2Z_{i}} \right)}}$

Preferably, the intermediate opening angle a1 i of each transition imageis determined as a weighted average between the opening angle a1 of theinitial synthesis image and the virtual opening angle a1′i, the weightcoefficients of which vary as a function of the transition moment ti atwhich the transition image is intended to be displayed.

In particular, the intermediate opening angle a1 i of each transitionimage is determined according to a function of the type:a1_(i)=(1−Y)*a1+Y*a1′_(j)

where Y, which varies between 0 and 1, is an increasing function of thetransition moment ti at which the transition image is intended to bedisplayed.

FIG. 9 shows an example function linking the transition moment ti, onthe x-axis, to the coefficient Y, on the y-axis, the scale on the x-axisbeing normalized between 0 and 1.

According to this example, the coefficient Y has a strictly increasingvalue between a first transition moment t1 and a median transitionmoment ti at which the coefficient Y assumes the value 1 and thenremains constant.

Such a determination of the intermediate opening angle a1 i and theobservation distance Di of each intermediate image makes it possible toobtain a fluid transition between the initial synthesis image and thefinal synthesis image.

The module 36 is also configured to generate a plurality of transitionimages between the initial synthesis image and the final synthesisimage, each transition image being seen from the intermediate openingangle a1 i and the intermediate observation distance Zi determined forthat transition image.

The module 36 is further configured to control the successive display bythe display device 14 of these transition images at the successivetransition moments ti, then to command the display by the display device14 of the final synthesis image, according to the second type ofperspective.

Similarly, during a transition between the initial synthesis imageaccording to the second type of perspective and a final synthesis imageaccording to the first type of perspective, the module 36 is configuredto generate three-dimensional transition images according to the firsttype of perspective by increasing, from one transition image to thenext, the opening angle a1 i, and decreasing, from one transition imageto the next, the observation distance Zi, such that the length A1 i ofthe zone represented by each transition image remains comprised in abounded interval around the length A1 of the zone shown by the finalsynthesis image. The final synthesis image may itself be considered atransition image.

The gradual increase of the opening angle a1 i from one transition imageto the next makes it possible to produce a fluid transition between thesynthesis image according to the second type of perspective and thesynthesis image according to the first type of perspective. Furthermore,the gradual decrease of the observation distance Zi makes it possible tokeep a zone length depicted by the transition images substantially equalto the length of the zone intended to be depicted by the final synthesisimage, and therefore contributes to providing a fluid transition betweenthe initial synthesis image and the final synthesis image.

The module 36 is thus configured to generate a first transition image,seen from a first intermediate opening angle a11 and with a firstintermediate observation distance Z1. The first intermediate openingangle is for example smaller than 10°, in particular equal to 5°. Thefirst intermediate observation distance is for example equal to 1600 km.

The module 36 is further configured to generate a plurality ofadditional transition images, each seen from an intermediate openingangle a1 i and an intermediate observation distance Zi.

The intermediate opening angle a1 i of each transition image is largerthan the intermediate opening angle of any previous transition image.

The intermediate opening angle a1 i of each transition image is thus anincreasing function of the transition moment at which that transitionimage is intended to be displayed.

“Increasing function” refers to a non-constant increasing function, asat least one first and one second successive transition moment exist,the second transition moment ti being after the first transition momentt_(i-1), such that the intermediate opening angle a1 _(i-1) of a firsttransition image intended to be displayed at the first moment isstrictly larger than the intermediate opening angle a1 i of a secondtransition image intended to be displayed at the second transitionmoment.

The intermediate opening angle a1 i of each transition image ispreferably a strictly increasing function of the transition moment atwhich that transition image is intended to be displayed.

The intermediate opening angle a1 i of each transition image is thusstrictly larger than the intermediate opening angle of any previoustransition image.

For example, the intermediate opening angle of the last transition imageis substantially equal to 90°.

The intermediate observation distance Zi of each transition image issmaller than the intermediate observation distance of any precedingtransition image.

The intermediate observation distance Zi of each transition image isthus a decreasing function of the transition moment at which thattransition image is intended to be displayed.

“Decreasing function” refers to a non-constant decreasing function, asat least one first and one second successive transition moment exist,the second transition moment ti being after the first transition momentt_(i-1), such that the intermediate opening angle a1 _(i-1) of a firsttransition image intended to be displayed at the first moment isstrictly smaller than the intermediate opening angle a1 i of a secondtransition image intended to be displayed at the second transitionmoment.

The intermediate observation distance Zi of each transition image ispreferably strictly smaller than the intermediate observation distanceof any preceding transition image.

The intermediate observation distance Zi of each transition image isthen a strictly decreasing function of the transition moment at whichthat transition image is intended to be displayed.

For example, the observation distance of the last transition image issubstantially equal to 100 m.

Preferably, the intermediate observation distance Zi of each transitionimage is a nonlinear decreasing function, in particular convex, of thetransition moment at which that transition image is intended to bedisplayed.

For example, the intermediate observation distance Zi is determinedaccording to a function symmetrical to that used during a transitionbetween a synthesis image according to the first type of perspective anda synthesis image according to the second type of perspective, asillustrated in FIG. 8.

Furthermore, the module 36 is preferably configured to determine theintermediate opening angle a1 i of each transition image as a functionof the intermediate observation distance Zi determined for thattransition image.

Preferably, the intermediate opening angle a1 i of each transition imageis a nonlinear increasing function of the transition moment ti at whichthat transition image is intended to be displayed.

In particular, the intermediate opening angle a1 i of a transition imageis determined as a function of the intermediate distance Zi such thatthe length of the zone depicted by the transition image is comprised ina predetermined bounded interval around the length A1 of the zonedepicted by the final synthesis image.

For example, the intermediate opening angle a1 i of each transitionimage is determined as a function of the opening angle a1 of the finalsynthesis image, the virtual opening angle a1′i and the transitionmoment ti at which the transition image is intended to be displayed.

Preferably, the intermediate opening angle a1 i of each transition imageis determined as a weighted average between the opening angle a1 of thefinal synthesis image and the virtual opening angle a1′i, the weightcoefficients of which vary as a function of the transition moment ti atwhich the transition image is intended to be displayed.

In particular, the intermediate opening angle a1 i of each transitionimage is determined according to a function of the type:a1_(i)=(1−Y′)*a1+Y*a1′_(i)where Y, which varies between 0 and 1, is a decreasing function of thetransition moment ti at which the transition image is intended to bedisplayed. For example, Y′ is such that:Y′(t _(i))=Y(t _(n) −t _(i)),

where Y is the function defined above, for example as illustrated inFIG. 9.

The module 36 is further configured to control the successive display bythe display device 14 of these transition images at the successivetransition moments ti, then to command the display by the display device14 of the final synthesis image, according to the first type ofperspective.

To generate a synthesis image according to the first perspective, themodule 36 associates each pixel of the three-dimensional environmentwith a depth attribute, representative of the altitude of that pixelrelative to a horizontal reference plane. Such an attribute in factmakes it possible for the module 36 only to display the objects nothidden by other objects on the synthesis image. The depth is includedover a predetermined number of bits, independent of the observationdistance.

Such encoding can cause a loss of precision of the encoding of the depthduring the display of images seen from a point of view very far from thecentral point of interest, and cause visual artifacts, in particularblinking effects, the module 36 no longer being able to determine whichpixel must be displayed on the screen due to this drop in precision.Such an effect could in particular occur during a transition between animage according to the first type of perspective and an image accordingto the second type of perspective or during a transition between animage according to the second type of perspective and an image accordingto the first type of perspective.

To avoid such an effect, the module 36 is configured to associate adepth attribute only with the pixels situated in a predefined zone, inparticular when the observation distance is greater than a predeterminedobservation distance. This predefined zone is defined as the set ofpixels situated at an altitude below a maximum predetermined altitude,and preferably above a predefined minimum altitude.

The maximum altitude is for example equal to 20 km. The minimum altitudeis for example defined as the altitude of the terrain.

Thus, for the pixels situated in the predefined zone, which is the onlyzone in which objects of interest may be found, the encoding of thedepth remains sufficiently precise to avoid the appearance of visualartifacts, even when the observation distance becomes very large, inparticular when the point of view is situated at an altitude above themaximum altitude.

One example method for viewing information related to a flight by anaircraft, implemented using a display system as previously described,will now be described in reference to FIG. 10.

In an initial step 200, the module 36 generates an initial synthesisimage and commands the display of that initial synthesis image on theviewing device 14, in particular in the window of the touchscreen 16with length L_(f) and width l_(f).

In the described example, the initial synthesis image is an imageaccording to the first type of perspective.

The initial synthesis image is centered on an initial central point ofinterest Pc₀, and seen from an initial point of view P_(v) situated atan initial distance Z0 from the initial central point of interest Pc₀.

The initial synthesis image is for example exocentric. In particular, itwill hereinafter be considered, as an example, that the initial centralpoint of interest Pc₀ corresponds to the position of the aircraft.

The initial synthesis image represents an observation volumesubstantially corresponding to a pyramid, with an initial horizontalopening angle a1 ₀ and an initial vertical opening angle a2 ₀.

The initial horizontal opening angle a1 ₀ is for example set by defaultat 90 degrees, the initial vertical opening angle a20 then being adaptedas a function of the length and width of the displayed image.

The initial vertical angular position av₀ can also be set by default,for example at a value of 30 degrees.

Furthermore, the initial observation distance Z₀ between the centralpoint of interest Pc₀ and the point of view Pv₀ is preferably chosensuch that a set of points of interest can be completely included in theobservation pyramid.

The initial horizontal angular position ah₀ can also be set by default,for example at a value of 0 degrees.

The initial synthesis image comprises a synthetic depiction of theenvironment situated in the vicinity of the trajectory of the aircraft,on which a curve representative of a portion of the trajectory of theaircraft in that environment is superimposed.

The initial synthesis image also shows, if applicable, one or moresymbolic objects, for example representative of the position of passagepoints, associated or not associated with constraints, altitude profilepoints associated with the trajectory of the aircraft, the position ofthe aircraft and/or objects that may interfere with the trajectory ofthe aircraft, for example clouds, storm cells or other aircraft.

The position of the point of view Pv₀ associated with the initialhorizontal position av₀ is not necessarily that making it possible toview the trajectory of the aircraft optimally.

Thus, the module 36 preferably automatically determines an optimalposition of the point of view making it possible to optimize thetrajectory portion viewed in the image.

In particular, the module determines, during a step 202, an optimizedposition of the point of view, situated at the distance Z₀ from thecentral point of interest Pc₀, situated at the vertical angular positionav₀ and at an optimized horizontal angular position a_(hopt) making itpossible to maximize the length of the trajectory portion viewed in theimage, the opening angles a1 and a2 remained fixed.

During step 202, the module 36 determines, during a phase 204, a set ofsuccessive points on the trajectory of the aircraft, denoted Pi,according to a predetermined sampling, from an initial point that forexample corresponds to the position of the aircraft, preferably in thedownstream direction of that trajectory. For example, the points Pi areregularly spaced apart on the trajectory.

The module 36 next adjusts, during a phase 205 or during a plurality ofsuccessive phases 205 carried out iteratively, the horizontal angularposition, from the initial horizontal angular position a_(h0), so as tosuccessively include the points Pi in the observation pyramid, whilemaintaining all of the points of interest in the observation pyramid.

Thus, during a first phase 205, the module 36 determines a firstmodified horizontal angular position a_(h1). To that end, the module 36determines a modified horizontal angular position such that the point P₁is included in the observation pyramid, preferably so that the edge ofthe observation pyramid closest to the point P₁ before modification ofthe initial horizontal angular position a_(h0) intersects the point P₁when the horizontal position is equal to that modified horizontalangular position.

If this modified horizontal angular position is not comprised in thepredefined authorized angular range for the horizontal angular position,the module 36 chooses, as first modified horizontal angular positiona_(h1), the boundary of this authorized range closest to the modifiedangular position thus determined.

If the modified vertical angular position is comprised in the predefinedauthorized angular range for the vertical angular position, the module36 chooses, as the first modified vertical angular position av1, thismodified angular position.

Then, during each following phase 205, the module 36 determines a newmodified horizontal angular position ahi. To that end, the module 36determines, during each phase, a modified horizontal angular positionsuch that the point Pi is included in the observation pyramid,preferably so that the edge of the observation pyramid closest to thepoint Pi before modification of the modified horizontal angular positionah_(i-1) determined during the preceding iteration of the phase 205intersects the point Pi when the horizontal angular position is equal tothat modified horizontal angular position.

Likewise, if the modified horizontal angular position is not comprisedin the predefined authorized angular range for the horizontal angularposition, the module 36 chooses the boundary of this authorized rangeclosest to the determined angular position as the new modifiedhorizontal angular position ahi.

If the modified horizontal angular position is comprised in thepredefined authorized angular range for the horizontal angular position,the module 36 is able to choose this modified angular position as newmodified horizontal angular position ahi.

During a final phase 205, the module 36 detects that it is not possibleto find a horizontal angular position such that the considered point Piof the trajectory is included in the observation pyramid without otherpoints of the trajectory or points of the set of points of interestleaving the observation pyramid, and then ends the sequence ofiterations. The optimal horizontal angular position a_(hopt) is thenchosen by the module 36 as the last determined modified angular positionah_(i-1).

The optimal horizontal angular position a_(hopt) is considered to be anew initial angular position.

The module 36 then determines a new initial point of view Pv₀ situatedat the initial distance Z₀ from the initial central point of interestPc₀, with an initial vertical angular position av₀ for example equal to30 degrees and an initial horizontal angular position ah₀ equal to theoptimal horizontal angular position a_(hopt).

The module 36 then generates, during a step 206, a new initial synthesisimage seen from the initial point of view Pv₀ and commands the displaythereof by the display device 14.

Several actions to modify this initial synthesis image by an operator,as well as the steps implemented by the system 10 following theseactions, will now be described successively.

In order to move the central point of interest along the trajectory ofthe aircraft, an operator selects the second modification mode of thecentral point of interest via the man-machine interface 18.

Then, during a step 211, the operator implements a modification actionfor the central point of interest, this action comprising moving acontrol member between an initial position and a final position. In thedescribed example, this action comprises a movement of a control member,for example an operator's finger or a stylus, between an initialposition and a final position on the touchscreen 16.

The module 36 detects this modification action during a step 212, andimplements, in a plurality of successive moments during this movement, aseries of steps in order to display, at each of these moments, amodified synthesis image centered on a modified point of interest.

In particular, at each of the successive moments, the module 36 detectsthe position of the control member during a step 213, this positionbeing comprised between the initial position and the final position, anddetermines, during a step 214, a modified central point of interestdenoted Pci as a function of the position of the control member at thatmoment. Each modified central point of interest Pci is situated alongthe curve 44.

This step 214 comprises a phase 215 for the determination by the module36, as a function of the movement vector between the initial position ofthe control member and its position at the considered moment, of acurvilinear distance over a curve representative of the trajectorybetween the initial central point of interest Pc₀ and the modifiedcentral point of interest Pci.

Preferably, this curvilinear distance is determined as a function of themovement vector and of a vector tangent to the curve at the initialcentral point of interest Pc₀, in particular as a function of a scalarproduct between a projection of the movement vector over a horizontalplane of the initial synthesis image and that tangent vector.

Step 214 next comprises a phase 216 for the determination, by the module36, of the position of the modified central point of interest Pci on thecurve 44 from the position on the curve of the initial central point ofinterest Pc₀ and the curvilinear distance determined during phase 215.

After step 214, the module 36 generates, during a step 217, a modifiedsynthesis image centered around the modified central point of interestPci, and commands the display of that modified synthesis image on thetouchscreen 16 during a step 218.

The sequence of steps 213, 214, 217 and 218 is implemented at aplurality of successive moments at least until the control memberreaches its final position.

Thus, during the action by the operator to modify the position of thecentral point of interest, the central point of interest remains, ateach moment, situated along the curve representative of the trajectoryof the aircraft, whatever the movement done by the operator.

In order to modify the scale of the synthesis image, i.e., in thedescribed example, to modify the observation distance Z, an operatorimplements an action during a step 221 to modify the scale via theman-machine interface 18.

This modification action comprises a movement of two control members, inparticular two of the operator's fingers, on the touchscreen 16 in twosubstantially opposite directions, which is followed in the describedexample by maintenance of the two control members on the touchscreen 16following their movement.

During a step 222, the module 36 detects this modification action, inparticular detects the positioning of the two members on the touchscreenacross from two separate initial points P₁ and P2, detects the positionof these two initial points, and determines an initial distance d₀between the initial points.

During a step 223, the module 36 determines a midpoint P_(m) situatedmidway between these two initial points P₁ and P2, as well as a firstzone 98, a second zone 100 and a third zone 102. The first, second andthird zones are preferably centered on the midpoint P_(m).

As described in reference to FIG. 6, the first, second and third zones98, 100, 102 are defined by a first closed curve C1 and a second closedcurve C2, situated within the first closed curve C1, the two curves C1and C2 preferably being centered on the midpoint P_(m).

The first zone 98, which includes the initial points P₁ and P2, isformed by the set of points contained between the first curve C1 and thesecond curve C2, the second zone 100 is formed by the set of pointscontained within the second curve C2, and the third zone 102 is formedby points situated outside the curves C1 and C2.

Then, during the scale modification action, the module 36 implements aseries of steps at a plurality of successive moments during the movementof the two control members in order to display, at each of thesemoments, a modified synthesis image on a modified scale.

In particular, at each of these moments, the module 36 determines theposition of the two control members during a step 224, then determines ascale modification factor □i□ as a function of this position during astep 225.

In particular, the module 36 determines, at each moment, denoted ti, thescale modification factor γ_(i) as a function of the position of thepoints across from which the control members are positioned relative tothe first zone 98.

If, at the considered moment ti, the control members remain positionedon the touchscreen 16 across from points situated inside the first zone98, the module 36 determines, during step 225, the sizing factor γ_(i)according to the first computation mode described above.

According to this first embodiment, the module 36 determines, at themoment ti, the scale modification factor γ_(i) as a function of thedistance d_(i) between the points across from which the control membersare positioned at that moment ti and the distance d₀ between the initialpoints P₁ and P2. Preferably, the scale modification factor γ_(i) is astrictly decreasing function of the distance di, for example a linearfunction of the deviation or the ratio between the distance d₀ and thedistance di.

If, on the contrary, at the considered moment ti, at least one of thecontrol members is positioned across from a point situated outside thefirst zone 98, i.e., inside the second zone 100 or the third zone 102,the module 36 determines, during step 225, the positioning factor γ_(i)according to the second computation mode described above.

According to this second computation mode, the module 36 determines, ateach moment t′i, the scale modification factor, denoted γ′_(i), as afunction of the maintenance duration of the control members outside thefirst zone 98. This maintenance duration, denoted Ti, corresponds to thetime elapsed between the moment denoted t′₀ at which one or two controlmembers have reached the boundaries of the first zone 98 and the momentt′i under consideration.

Preferably, according to this second computation mode, the controlmembers are positioned on the touchscreen 16 across from points situatedoutside the first zone 98, the scale modification factor □′i isindependent of the position of the points of the screen situated acrossfrom these control members.

Then, during a step 226, the module 36 applies the scale modificationfactor γ_(i) or γ′_(i) determined at the considered moment to theinitial synthesis image to determine a modified scale. In particular, inthe described example, the module 36 determines a modified observationdistance Zi by applying a factor γ_(i) or γ′_(i) to the initial distanceZ₀, and determines a new point of view situated at the distance Zi fromthe central point of interest.

During a step 227, the module 36 generates a modified image at themodified scale thus determined, and commands the display of thismodified synthesis image on the touchscreen 16 during a step 228.

Thus, during a scale modification action, the module 36 determines thescale modification factor according to the first computation mode, i.e.,as a function of the distance d_(i) between the opposite points at whichthe control members are positioned as long as these points remainsituated in the first zone 98, then, once at least one of these pointsleaves the first zone 78, the module 36 determines the scalemodification factor according to the second computation mode, i.e., as afunction of the maintenance duration of the point(s) outside the firstzone.

The sequence of steps 224, 225, 226, 227 and 228 is implemented at aplurality of successive moments at least until the control members arereleased from the touchscreen 16.

Once the control members are no longer positioned on the touchscreen 16,the modification action of the dimensions of the zone displayed by thesynthesis image stops.

Preferably, during a step 228, the module 36 compares the dimensionsA_(1n) and A_(2n) or the distance Z_(n) associated with the lastgenerated modified image to predetermined dimension or distancethreshold, and determines the dimension thresholds, the distancethreshold, respectively, closest to the dimensions A_(1n) and A_(2n) orthe distance Z_(n).

The module 36 then generates a final modified image depicting a zonewhereof the dimensions correspond to the closest dimension thresholdsdetermined and/or seen from a distance Z equal to the determineddistance threshold, and commands the display thereof on the touchscreen16.

To go from the initial synthesis image according to the first type ofperspective to a synthesis image according to the second type ofperspective, for example seen from above, during a step 231, theoperator performs a modification action using the man-machine interface18, for example by actuating a dedicated icon superimposed on thesynthesis image by the module 36.

During a step 232, the module 36 detects this modification action, thengenerates, during a plurality of successive steps 233, a plurality ofsuccessive transition synthesis images between the initial synthesisimage according to the first type of perspective and the synthesis imageaccording to the second type of perspective.

The transition images are intended to be displayed on the viewing device14 at a plurality of successive transition moments ti, between aninitial display moment of the initial synthesis image and a finaldisplay moment of the synthesis image according to the second type ofperspective.

Each transition image generated during a step 233 is an image accordingthe first type of perspective.

Each transition image generated during a step 233 is centered around anintermediate central point of interest Pci, is seen from an intermediatepoint of view Pvi, situated at an intermediate observation distance Zi,and is seen from an intermediate horizontal opening angle a1 i and anintermediate vertical opening angle a2 i. Each transition image depictsa zone of the environment with an intermediate length A1 i andintermediate width A2 i, the ratio between the intermediate length A1 iand the intermediate width A2 i remaining constant and equal to theratio between the length A1 and the width A2 of the three-dimensionalsynthesis image. As indicated above, the horizontal a1 i and vertical a2i intermediate opening angles being connected to one another as afunction of the ratio between the intermediate length A1 i and theintermediate width A2 i that remains constant, the “opening angle” willhereinafter generally refer to one or the other of these opening angles,for example the intermediate horizontal opening angle a1 i.

Each step 233 comprises a phase 235 for the determination, by the module36, of the intermediate opening angle a1 i and the intermediateobservation distance Zi of the transition image intended to be displayedat the transition moment ti associated with that step.

As explained above, the opening angle a1 i of each transition image isthus a decreasing function, preferably strictly decreasing, of thetransition moment ti at which this transition image is intended to bedisplayed, and the intermediate observation distance Zi of eachtransition image is an increasing function, preferably strictlyincreasing, of the transition moment at which this transition image isintended to be displayed.

Preferably, the intermediate observation distance Zi of the transitionimage is determined during each phase 235 according to a nonlinearincreasing function, in particular convex, of the transition moment atwhich this transition image is intended to be displayed, as illustratedin FIG. 7.

Furthermore, during each phase 235, the module 36 determines theintermediate opening angle a1 i of the transition image as a function ofthe intermediate observation distance Zi determined for that transitionimage, according to a nonlinear decreasing function of the transitionmoment ti at which this transition image is intended to be displayed.

In particular, the intermediate opening angle a1 i of a transition imageis determined as a function of the intermediate observation distance Zisuch that the length of the zone depicted by the transition image iscomprised in a predetermined bounded interval around the length A1 ₀ ofthe zone depicted by the three-dimensional initial synthesis image.

For example, the intermediate opening angle a1 i of each transitionimage is determined as a function of the opening angle a1 ₀ of theinitial three-dimensional synthesis image, the virtual opening anglea1′i and the transition moment ti at which the transition image isintended to be displayed.

Preferably, during each phase 235, the intermediate opening angle a1 iof the transition image is determined as a weighted average between theopening angle a1 ₀ of the initial synthesis image and the virtualopening angle a1′i, the weight coefficients of which vary as a functionof the transition moment ti at which the transition image is intended tobe displayed.

In particular, the intermediate opening angle a1 i is determined duringeach phase 235 according to a function of the type:a1_(i)=(1−Y)*a1₀ +Y*a1′_(i).

Each phase 235 is followed by a phase 236 for generating a transitionimage seen along the intermediate opening angle a1 i and theintermediate observation distance Zi determined for that transitionimage during phase 235.

Each step 233 for generating a transition image is followed by a step238 for the command, by the module 36, of the display of that transitionimage by the display device 14 at the transition moment ti associatedwith that transition image.

The gradual increase of the opening angle a1 i from one transition imageto the next makes it possible to produce a fluid transition between thesynthesis image according to the first type of perspective and thesynthesis image according to the second type of perspective.Furthermore, the gradual decrease of the observation distance Zi makesit possible to keep a zone length depicted by the transition imagessubstantially identical to the length of the zone intended to bedepicted by the synthesis image according to the second type ofperspective and therefore contributes to providing a fluid transitionbetween the initial synthesis image according to the first type ofperspective and the final synthesis image according to the second typeof perspective.

Then, following the set of successive steps 233 and 238, during a step239, the module 36 generates a synthesis image according to the secondtype of perspective and commands the display thereof by the viewingdevice 14 during a step 240.

Preferably, the synthesis image according the second type ofperspective, as well as the transition images, are centered on the samecentral point of interest as the initial synthesis image t according tothe first type of perspective. Furthermore, the length and width of thezone depicted by the final image are substantially equal to the lengthand width of the zone depicted by the initial image.

Similarly, to go from the initial synthesis image according to thesecond type of perspective to a final synthesis image according to thefirst type of perspective, during a step 241, the operator performs amodification action using the man-machine interface 18, for example byactuating a dedicated icon superimposed on the synthesis image by themodule 36.

During a step 242, the module 36 detects this modification action, thengenerates, during a plurality of successive steps, a plurality ofsuccessive transition synthesis images between the initial synthesisimage and the final synthesis image.

The transition images are intended to be displayed on the viewing device14 at a plurality of successive transition moments ti, between aninitial display moment of a first transition image and a final displaymoment of the final synthesis image according to the first type ofperspective.

During a first step 243, the module 36 generates the first transitionimage. During this step 243, the module 36 determines a first smallintermediate opening angle a11 and a first large intermediateobservation distance Z1. The first intermediate opening angle is forexample equal to 5°. The first intermediate observation distance is forexample equal to 1600 km.

Then, the module 36 generates the first transition image. The firsttransition image is centered around an intermediate central point ofinterest Pc1, is seen from an intermediate point of view Pv1, situatedat the intermediate observation distance Z1 from the intermediatecentral point of interest Pc1. The first transition image is furtherseen from the intermediate horizontal opening angle a11 and anassociated intermediate vertical opening angle a21.

Then, during a plurality of successive steps 244, the module 36generates a plurality of successive transition synthesis images betweenthe first transition image and the final three-dimensional synthesisimage.

Each transition image generated during a step 244 is an image accordingto the first type of perspective.

Each transition image generated during a step 244 is centered around acentral intermediate point of interest Pci, is seen from an intermediatepoint of view Pvi, situated at an intermediate observation distance Zi,and is seen along an intermediate opening angle a1 i.

Each step 244 comprises a phase 245 for the determination, by the module36, of the intermediate opening angle a1 i and the intermediateobservation distance Zi of the transition image intended to be displayedat the transition moment ti associated with that step.

As explained above, the opening angle a1 i of each transition image isthus an increasing function, preferably strictly increasing, of thetransition moment ti at which this transition image is intended to bedisplayed, and the intermediate observation distance Zi of eachtransition image is a decreasing function, preferably strictlydecreasing, of the transition moment ti at which this transition imageis intended to be displayed, such that the zone displayed by thesuccessive transition images remains substantially the same.

Preferably, the intermediate observation distance Zi of the transitionimage is determined during each phase 245 according to a nonlineardecreasing function, in particular convex, of the transition moment atwhich this transition image is intended to be displayed, as illustratedin FIG. 7.

Furthermore, during each phase 245, the module 36 determines theintermediate opening angle a1 i of the transition image as a function ofthe intermediate observation distance Zi determined for that transitionimage, according to a nonlinear increasing function of the transitionmoment ti at which this transition image is intended to be displayed.

In particular, the intermediate opening angle a1 i of a transition imageis determined as a function of the intermediate distance Zi such thatthe length of the zone depicted by the transition image is comprised ina predetermined bounded interval around the length of the zone intendedto be depicted by the final synthesis image, which is substantiallyequal to the length of the zone depicted by the initial synthesis imageand the length of the zone depicted by the first transition image.

For example, the intermediate opening angle a1 i of each transitionimage is determined as a function of the opening angle a11 of the finalsynthesis image, the virtual opening angle a′1 i defined above, and thetransition moment ti at which the transition image is intended to bedisplayed.

For example, the intermediate opening angle a1 i of each transitionimage is determined, during phase 245, as a function of the openingangle a1 of the final synthesis image, the virtual opening angle a1′iand the transition moment ti at which the transition image is intendedto be displayed, as indicated above.

Each phase 245 is followed by a phase 246 for generating a transitionimage seen along the intermediate opening angle a1 i and theintermediate observation distance Zi determined for that transitionimage during phase 245.

Each of steps 243 and 244 is followed by a control step 248 for thecommand, by the module 36, of the display of that transition image bythe display device 14 at the transition moment ti associated with thattransition image. The last transition image corresponds to the finalimage.

It must be understood that the example embodiments described above arenot limiting.

In particular, according to one alternative, the tactile control deviceis separate from the display device 14. For example, the tactile controldevice is a trackpad.

According to one alternative, the man-machine interface comprises, toreplace or in addition to the tactile control device, one or morecontrol members, for example a mouse or joystick and/or a keyboard, avirtual rotator, etc.

For example, an action to modify the position of the central point ofinterest of the first or second type described above may consist of amovement of an object, such as a cursor, over the displayed synthesisimage, using a control member, up to an icon 80 or any position on thesynthesis image, for example followed by actuation of a key of akeyboard or a button. A modification action of the position of thecentral point of interest of the third type described above may alsoconsist of moving an object, such as a cursor, on the displayedsynthesis image, using a control member, while keeping a button or keyactuated.

Furthermore, the synthesis images generated and displayed do notnecessarily reflect the environment of the aircraft and its position inreal-time. In particular, the synthesis images may correspond to asimulation of the flight of the aircraft or a particular phase of theflight of the aircraft be displayed before, during or after that flightor phase. For example, synthesis images illustrating an approach phaseof the aircraft may be displayed during the flight of the aircraft,before this approach phase.

What is claimed is:
 1. A system for displaying information related to aflight of an aircraft, the system comprising: a display; a dynamicsynthesis image generator configured to dynamically generate synthesisimages on the display, each synthesis image comprising a syntheticdepiction of the environment situated in the vicinity of a trajectory ofthe aircraft and a curve representative of a trajectory of the aircraft,each synthesis image being centered on a central point of interest inthe synthetic depiction, the curve being superimposed on the syntheticdepiction, the dynamic synthesis image generator being configured togenerate a first synthesis image centered on a first central point ofinterest, the first central point of interest being a point located atthe center of the first synthesis image, and to command displaying of,on the display, the first synthesis image; and a man-machine interface,the dynamic synthesis image generator being configured to detect amodification action to modify a position of the central point ofinterest in the synthetic depiction by an operator via the man-machineinterface, the modification action to modify the position of the centralpoint of interest in the synthetic depiction comprising a movement of acontrol member by the operator between a first member position and asecond member position, the control member being: a stylus or a fingerof the operator movable along a surface from the first member positionto the second member position, or configured to displace a cursor on thesynthesis image when the control member is moved from the first memberposition to the second member position, the dynamic synthesis imagegenerator being further configured to: determine, as a function of themodification action, a position of a second central point of interest,situated along the curve representative of the trajectory of theaircraft, the second central point of interest being distinct from thefirst central point of interest and being situated along the curvewhatever the modification action is, without it being necessary for theoperator to move the control member in a direction corresponding, ateach moment, to the direction of the trajectory, generate, in responseto the modification action, a second synthesis image centered on thesecond central point of interest, and command the display, in responseto the modification action, on the display, of the second synthesisimage, the second central point of interest situated along the curverepresentative of the trajectory of the aircraft being a point locatedat the center of the second synthesis image.
 2. The system according toclaim 1 wherein the first central point of interest is situated alongthe curve, and the modification action to modify the position of thecentral point of interest comprises a movement of the control member bythe operator between the first member position and the second memberposition in a direction not parallel to the tangent to the curve at thefirst central point of interest.
 3. The system according to claim 1wherein the first central point of interest is situated along the curve,and the dynamic synthesis image generator is configured to: determine,as a function of a movement vector between the first member position andthe second member position, a curvilinear distance on the curve betweenthe first central point of interest and the second central point ofinterest; and to determine, from a position on the curve of the firstcentral point of interest and the curvilinear distance, the position onthe curve of the second central point of interest.
 4. The systemaccording to claim 3 wherein the dynamic synthesis image generator isconfigured to determine the curvilinear distance as a function of themovement vector and a vector tangent to the curve at the initial centralpoint of interest.
 5. The system according to claim 4 wherein thedynamic synthesis image generator is configured to determine thecurvilinear distance as a function of a scalar product between aprojection of the movement vector over a horizontal plane of the firstsynthesis image and the vector tangent to the curve.
 6. The systemaccording to claim 1 wherein the synthesis images are three-dimensionalimages, the synthetic depiction of the environment being athree-dimensional depiction and the curve being a three-dimensionalcurve.
 7. The system according to claim 1 wherein the first synthesisimage is seen from a first point of view, and the dynamic synthesisimage generator is configured to detect a rotation action of a positionof the first point of view relative to the first central point ofinterest in a vertical plane, or in a horizontal plane, respectively,the rotation action comprising a movement of the control member by theoperator in a vertical direction, or in a horizontal direction,respectively, the dynamic synthesis image generator being furtherconfigured to determine, as a function of the rotation action, amodified point of view, to generate a modified synthesis image seen fromthe modified point of view, and to command the display, on the display,of the modified synthesis image.
 8. The system according to claim 7wherein the dynamic synthesis image generator is configured to display avertical slide and/or a horizontal slide on the first synthesis image,and the rotation action comprises a movement of the control member bythe operator on the vertical slide, or the horizontal slide,respectively, in the vertical direction, or in the horizontal direction,respectively.
 9. The system according to claim 1, wherein the firstcentral point of interest is positioned on a current location of theaircraft and the second central point of interest is positioned on aprojected future location of the aircraft.
 10. The system according toclaim 1, wherein the first member position and the second memberposition are located on the synthesis image.
 11. The system according toclaim 1, wherein a movement vector of the movement of the member betweenthe first member position and the second member position includes ahorizontal component in a horizontal plane of the synthesis image, andregardless of a direction of the movement of the member between thefirst member position and the second member position, the second centralpoint of interest being calculated as a function of the horizontalcomponent of the movement vector.
 12. The system according to claim 1,wherein the control member configured to displace the cursor on thesynthesis image when the control member is moved from the first memberposition to the second member position is selected amongst a mouse, ajoystick and a virtual rotator.
 13. The system according to claim 1,wherein the man-machine interface comprises a tactile control device,the control member is the stylus or the finger of the operator, and theaction to modify the central point of interest comprises the movement ofthe control member by the operator between the first position and thesecond position on the tactile control device.
 14. A method fordisplaying information related to a flight of an aircraft, wherein themethod comprises the following successive steps: displaying, on adisplay, a first synthesis image comprising a synthetic depiction of theenvironment situated in the vicinity of a trajectory of the aircraft anda curve representative of a trajectory of the aircraft, each synthesisimage being centered on a central point of interest in the syntheticdepiction, the curve being superimposed on the synthetic depiction, thefirst synthesis image being centered on a first central point ofinterest, the first central point of interest being a point located atthe center of the first synthesis image; detecting a modification actionto modify a position of the first central point of interest in thesynthetic depiction by an operator via a man-machine interface, themodification action to modify the position of the central point ofinterest in the synthetic depiction comprising a movement of a controlmember by the operator between a first member position and a secondmember position, the control member being: a stylus or a finger of theoperator movable along a surface from the first member position to thesecond member position, or configured to displace a cursor on thesynthesis image when the control member is moved from the first memberposition to the second member position; determining, as a function ofthe modification action, a position of a second central point ofinterest, the second central point of interest being distinct from thefirst central point of interest and being situated along the curvewhatever the modification action is, without it being necessary for theoperator to move the control member in a direction corresponding, ateach moment, to the direction of the trajectory; generating, in responseto the modification action, a second synthesis image centered on thesecond central point of interest; and displaying, in response to themodification action, the second synthesis image on the display, thesecond central point of interest situated along the curve representativeof the trajectory of the aircraft being a point located at the center ofthe second synthesis image.
 15. The system according to claim 1, whereinthe movement of the control member by the operator between the firstmember position and the second member position includes movementvectors, the control member being: the stylus or the finger of theoperator movable at the movement vectors along the surface from thefirst member position to the second member position, or configured todisplace the cursor on the synthesis image when the control member ismoved at the movement vectors from the first member position to thesecond member position.
 16. The system according to claim 15, whereinthe position of the second central point of interest, along the curverepresentative of the trajectory of the aircraft is determined asfunction of the movement vectors.
 17. The method according to claim 14,wherein the man-machine interface comprises a tactile control device,the control member is the stylus or the finger of the operator, and theaction to modify the central point of interest comprises the movement ofthe control member by the operator between the first position and thesecond position on the tactile control device.
 18. The method accordingto claim 17 wherein the first central point of interest is situatedalong the curve, and the modification action to modify the position ofthe first central point of interest comprises a movement of the controlmember by the operator between the first member position and the secondmember position in a direction not parallel to the tangent to the curveat the first central point of interest.
 19. The method according toclaim 17 wherein the modification action to modify the position of thefirst central point of interest comprises a movement of the controlmember by the operator between the first member position and the secondmember position on a touchscreen.
 20. The method according to claim 17wherein the first central point of interest is situated along the curve,and the determining of the position of the second central point ofinterest comprises: determining, as a function of a movement vectorbetween the first member position and the second member position, acurvilinear distance on the curve between the first central point ofinterest and the second central point of interest; and determining, froma position on the curve of the first central point of interest and thecurvilinear distance, the position of the second central point ofinterest.
 21. The method according to claim 20 wherein the curvilineardistance is determined as a function of the movement vector and a vectortangent to the curve at the first central point of interest.
 22. Themethod according to claim 21 wherein the curvilinear distance isdetermined as a function of a scalar product between a projection of themovement vector over a horizontal plane of the first synthesis image andthe vector tangent to the curve.
 23. The method according to claim 17,wherein the first central point of interest is positioned on a currentlocation of the aircraft and the second central point of interest ispositioned on a projected future location of the aircraft.
 24. Themethod according to claim 17, wherein the first member position and thesecond member position are located on the synthesis image.
 25. Themethod according to claim 17, wherein a movement vector of the movementof the member between the first member position and the second memberposition includes a horizontal component in a horizontal plane of thesynthesis image, and regardless of a direction of the movement of themember between the first member position and the second member position,the second central point of interest being calculated as a function ofthe horizontal component of the movement vector.
 26. The methodaccording to claim 17, wherein the control member displacing the cursoron the synthesis image is selected amongst a mouse, a joystick and avirtual rotator.